
Glass _ 
Book. 



COPYRIGHT DEPOSIT 



THE 



Essentials of Anatomy 



DESIGNED AS A TEXT-BOOK FOR STUDENTS 

AND AS A 

BOOK OF EASY REFERENCE FOR THE PRACTITIONER 



BY 



WILLIAM DARLING, M.D. F.R.C.S. 

PROFESSOR OF ANATOMY IN THE MEDICAL DEPARTMENT OF THE 
NEW YORK UNIVERSITY 



AMBROSE L? RANNEY, A.M. M.D. 

ADJUNCT PROFESSOR OF ANATOMY IN THE MEDICAL DEPARTMENT OF TH] 
NEW YORK UNIVERSITY 



Ul 



( 



^ 






NEW YORK 

G. P. PUTNAM'S SONS 

182 FIFTH AVENUE 
I88O 



r 



^0 



COFYRIGHT, 1880, BY G. P. PUTNAM'S SONS, New YORK. 



PREFACE 



It may seem to the members of the medical profession, a 
needless task to present another work upon Anatomy, when so 
many exhaustive treatises already exist ; and the criticism is one 
in which the Authors of this volume might justly coincide were 
the present work intended to supercede or rival the works of such 
famous authors as Quain, Gray, Ellis, Sappey, Hyrtl> Holden, 
Wilson, Heath, Bellamy, and others who have merited enduring 
reputation. 

It is to be hoped, however, that the public will agree with 
the Authors of this volume in the feeling that the more exhaust- 
ive treatises, in all their completeness of detail, often compel the 
student, in the beginning of his studies, to waste much valuable 
time in culling, from the voluminous mass of matter before him, 
such points as seem to him essential, and that, too often, these 
selections are not made with the judgment which the enlighten- 
ment of continued study and a higher degree of culture would 
afford. 

The present state of advanced science and the practical bear- 
ing which minute anatomical points and microscopical discoveries 
in histology are assuming, all tend, possibly too often, to lead 
anatomical instructors to forget that the medical student must 
creep before he can walk, and that by a thorough comprehension 
of those anatomical facts which are comprised in gross anatomy 
only, can he either appreciate or properly value the higher grades 
of anatomical investigation. 

It is, at present, too common, with critics to stamp with their 
opprobrium all works which are not diffuse in character, and to 
stigmatize, as " cram'books," any which show an attempt to sim- 
plify, condense, and rearrange facts hitherto well known ; and to 
refer their readers to treatises whose exhaustiveness alone per- 
haps, requires the very preparatory drill which a smaller volume 
of well-culled facts would best afford them. 

In this volume will be found, wliat, in the opinion of the 
authors at least, are some, perhaps not all, of the essentials of 
human anatomy. 

It has been the endeavor of the Authors to so arrange these 
anatomical facts as to render their comprehension easy, even to 



IV PREFACE. 

the beginner ; while they have aimed also to render it a volume 
of easy reference to the Surgeon and Practitioner. 

Much of the matter contained has been tabulated and ar- 
ranged in such a systematic form as to render the perusal of page 
after page of printed matter unnecessary, and, as far as possible, 
all points, having a practical bearing, have been so mentioned. 

It will be observed, possibly to its detriment in the opinion 
of some, that this volume deals principally with anatomical facts, 
rather than with questionable microscopical discoveries, since, 
however valuable the latter may be as a step towards positive 
knowledge, they are constantly changing with the advance of 
science, and can be best acquired from the exhaustive treatises 
which are from time to time appearing upon these subjects. 

To the casual reader, there may seem, throughout this work, 
a redundancy of expression, which might have been avoided ; 
but, as this book has been partly devised to aid reference among 
the general practitioners of medicine, who have, too often, little 
time for further reading than is demanded to gain the point sought 
for, it has been deemed expedient to render each descriptive para- 
graph as little dependent upon those preceding it, as possible. 

The few diagrammatic illustrations, which are contained within 
this volume, are presented rather as a means of impressing some 
particular points than as accurate representations of the parts 
under consideration. 

Many of the valuable tables contained in the chapters upon 
osteology and myology, have been for years a part of the course 
of lectures of Professor Darling before the classes of the Medical 
Department of the New York University, and have appeared in 
print in Europe, while many new ones have been added to sim- 
plify other branches of the subject. 

As this work has not been intended to supplant, but rather to 
accompany more exhaustive treatises, the absence of illustrations 
will not materially detract from its usefulness, since even begin- 
ners in medicine would hardly be well equipped for their work 
without some one of the standard text-books, while to the prac- 
titioner of medicine or surgery, in whose libraries are probably 
contained volumes replete with illustrations, this work is given 
to simplify anatomical review and to aid easy reference. 

It seems especially important to the Authors that the explan- 
atory matter connected with most of the tables and diagrams of 
this work should be perused with care, before they are used as 
aids to study or reference, since both will be greatly simplified 
by so doing. 



PREFACE. V 

The Authors here acknowledge their indebtedness to all of 
those investigators of Anatomy who have put into print the 
results of their researches, since it is impossible to depart, in 
many instances, from methods of arrangements, which have pre- 
viously been given to the public, or to avoid the free use of much 
that, in other volumes, seems particularly valuable and worthy 
of perpetuation. 



GENERAL INTRODUCTION. 



Anatomy, its definition Page I 

Classification of its varieties 

Definitions of its numerous divisions 

Animal anatomy, its component parts 

Names applied to treatises on special departments of animal anatomy 

The solids of the human body 

The fluids of the human body 



PART I. 

OSTEOLOGY. 
Division A. 

The skeleton as a whole Page 7 

Diyision B. 

The bones of the cranium " 17 

Division C. 

The bones of the face. " 45 

Division D. 

The skull in general, its cavities, fossae and foramina " 61 

Division E. 

The skeleton of the trunk " 76 

(a) The vertebral column " 79 

(b) The skeleton of the thorax " 93 

(c) The bones of the pelvis " 103 

Division F. 

The skeleton of the upper extremity " 120 

(a) The bones of the shoulder " 121 

(b) The bones of the arm " 127 

(c) The bones of the fore-arm " 132 

(d) The bones of the hand " 14c 

Division G. 

The skeleton of the lower extremity " 147 

(a) The bones of the thigh " 147 

(b) " " " leg "152 

(c) " *' " foot « 156 

PART II. 

ARTHROLOGY. 

General Introduction Page 167 

The structure of joints in general " 167 

The varieties of ligaments " 167 

The varieties of cartilage « 16S 



viii GENERAL INTRODUCTION. 

The varieties of fibro- cartilage Page 168 

The varieties of synovial membranes " 168 

Diagram of the varieties of joints , " 168 

Movements possible to joints " 169 

Division A. 

Articulations of the cranium with the spine " 170 

(a) Occipito-atloid articulation " 170 

(b) Occipito-axoid articulation " 171 

(c) Atlo-axoid articulation " 171 

Division B. 

Articulations of the vertebrae H 172 

Division C. 

Articulations of the ribs " 173 

(a) Costo-vertebral articulations " 173 

(b) Costo-transverse articulations " 173 

(c) Chondro-sternal articulations " 174 

(d) Chondro-costal articulations " 174 

Division D. 

Articulations of the pelvis " 175 

(a) Sacro- iliac articulation " 175 

(b) Pubic articulation " 175 

(c) Sacro-coccygeal articulation " 176 

(d) Sacro-vertebral articulation " 176 

Division E. 

The temporo -maxillary articulation " 176 

Division F. 

Articulations of the upper extremity. " 177 

(1) Sterno-clavicular articulation " 177 

(2) Acromio-clavicular articulation " 178 

The ligaments of the scapula " 179 

(3) The shoulder-joint " 179 

(4) The elbow-joint *' 180 

(5) The radioulnar articulations * " 181 

Superior articulation " 181 

Middle articulation " 181 

Inferior articulation " 181 

(6) The wrist-joint % " 182 

(7) Articulations of the carpus " 183 

(8) Carpo-metacarpal articulations " 184 

(9) Metacarpo-metacarpal articulations. " 184 

(10) Metacarpophalangeal articulations 185 

(n) Phalangeal articulations . 185 

Division G. 

Articulations of the lower extremity 186 

(1) The hip-joint " 186 

(2) The knee-joint " 19° 

(3) The tibio-fibular articulations *94 

Superior articulation IQ 4 

Middle articulation T 94 

Inferior articulation T 94 

(4) The ankle-joint " 195 

(5) Articulations of the tarsus x 9^ 

(6) Tarso-metatarsal articulations • x 9& 



GENERAL INTRODUCTION. 



IX 



(7) Metatarso-metatarsal articulations Page 199 

(8) Metatarsophalangeal articulations " 199 

(9) Phalangeal articulations " 199 

PART III. 



MYOLOGY. 

INTRODUCTION. 

Classification of muscles , 

Various forms of muscles 

Variations in the arrangement of fibres to tendon 

The nomenclature of muscles 

Situation of striated and unstriated muscular fibres 

Division A. 

Muscles of the head 

Epicranial group 

Auricular group 

Palpebral group 

Nasal group , 

Orbital group 

Labial group 

Maxillary group 

Summary of muscles of the head . . . . , 

Division B. 

Muscles of the Neck 

Superficial lateral group , 

Infra or sterno-hyoid group 

Supra or genio-hyoid group 

Submaxillary or stylo-hyoid group , 

Preverbetral group 

Posterior cervical group , 

Muscles of the palate 

Muscles of the pharynx 

Muscles of the larynx , 

Boundaries of the triangles of the neck 

Division C. 

Muscles of the trunk 

(a) Muscles of the abdomen , 

(b) Muscles of the thorax , 

(c) Muscles of the back 

(d) Muscles of the perineum 

(e) The cavities of the trunk, their boundaries and contents.. 
Division D. 

Muscles of the upper extremity. 

I. Extrinsic muscles 

II. Intrinsic muscles 

(a) Muscles of the scapulo-humeral region 

(b) Muscles of the arm 

(c) Muscles of the fore-arm 

(d) Muscles of the hand 

General summary of the muscles of the upper extremity. 

Division E. 

Muscles of the lower extremity.. . •. 

I. Muscles of the iliac region 



203 
203 
203 
204 
204 

205 
206 
206 
207 
208 
209 
2ro 
213 
214 

2J5 

216 

217 
218 

220 
221 
223 
225 
226 
229 
231 

236 
237 
245 
249 
26l 
264 



266 
270 
272 

277 
2Sl 
29I 

200 

302 



GENERAL INTRODUCTION. 

II. Muscles of the femoral region Page 304 

The anterior femoral group " 304 

The internal femoral group •* 306 

The gluteal or superio-posterior group " 308 

The posterior femoral group " 310 

III. Muscles of the popliteal region " 313 

IV. Muscles of the crural region " 314 

The anterior group " 314 

The superficial posterior group " 315 

The deep posterior group " 316 

The lateral or peroneal group " 317 

V. Muscles of the pedal region M 319 

The dorsal set " 316 

The plantar set " 319 

Summary " 324 

VI. General summary of the muscles of the lower 

extremity " 327 

PART IV. 

ANGIOLOGY. 



Introduction " 333 

The arterial system as a whole ' " 333 

Collateral circulation of arteries " 334 

Structure of the arterial coats " 336 

Nerve supply to the coats of arteries '* 337 

Division A. 

The arch of the aorta " 338 

Its ascending portion " 338 

Its transverse portion " 340 

Its descending portion " 341 

Surgical anatomy of the aortic arch " 341 

Branches of the arch of the aorta " 344 

Division B. 

The arteria innominata " 345 

Division C. 

The arteries of the head and neck " 346 

Division D. 

The surgical triangles of the neck " 365 

Division E. 

The arteries of the upper extremity " 371 

Division F. 

The arteries of the trunk " 399 

Division G. 

The arteries of the lower extremity " 405 

Division H. 

The veins of the body " 420 

Veins of the head and neck " 422 

Sinuses of the dura mater " 423 

Veins of the trunk " 425 

Superior vena cava " 425 

Inferior vena cava " 425 



GENERAL INTRODUCTION-. 



XI 



The azygos veins, Page 425 

The portal system of veins " 4 2 5 

Veins of the pelvis " 4 2 7 

Veins of the upper extremity " 427 

Veins of the lower extremity " 428 

Division I. 

The lymphatic system « " 43° 

The thoracic duct " 431 



PART V. 



NEUROLOGY. 



General Introduction. 

Varieties of nerve tissue M 437 

Structure of nerves , " 437 

Varieties of nerves " 437 

Division A. 

The cerebro-spinal axis, considered as a whole " 437 

The membranes of the brain and spinal cord " 439 

Division B. 

Structure of the encephalon or brain " 441 

Enumeration of its twelve ganglia and their general situation . . " 441 

Enumeration of the commissures of the brain " 443 

The cavities of the brain and their boundaries " 444 

The cerebrum " 448 

Its principal lobes. " 449 

Its principal fissures " 449 

Its inner surface, and its points of interest " 451 

Its inferior surface, and its points of interest . . . " 452 

Its internal structure, and the important parts contained with- 
in it " 453 

The corpus striatum , , . " 453 

The optic thalamus , ,. " 454 

The fornix " 454 

The corpus callosum " 456 

The meso-cephalon " 456 

The pons-varolii " 457 

The crura cerebri , " 457 

The valve of Vieussens , " 457 

The tubercula quadrigemina " 487 

The pineal gland ,....,.... " 458 

The medulla-oblongata , , u 458 

Its fissures " 458 

Its component parts " 45S 

Its nuclei of grey matter " 45S 

The cerebellum " 459 

Its surfaces and their points of interest " 459 

Its fissures M 460 

Its processes " 460 

General summary of the brain " 461 



Xii GENERAL INTRODUCTION. 

Division C. 

The spinal cord , Page 463 

Its columns " 463 

Its fissures " 463 

Its nerves , . . . . " 463 

Its grey matter. . -. . " 463 

Its fibres and their distribution " 463 

Division D. 

The cerebro-spinal nerves " 465 

The cranial nerves, tables of t ........ " 466 

Summary of. .-. , . „ oc . " 469 

The nerves of the cervical region, tables of " 475 

Summary of " 477 

The nerves of the upper extremity, tables of " 478 

Summary of " 482 

The nerves of the dorsal region, table of " 484 

Summary of " 485 

The nerves of the lumbar region, tables of " 4S6 

Summary of " 48 9 

The nerves of the sacral region, tables of " 490 

Summary of " 492 

The nerves of the leg and foot, tables of . . . , " 493 

Summary of , " 495 

Division E. 

The sympathetic nerve " 497 

Its ganglia , " 497 

Its plexuses .- " 498 

Its cords of communication , " 500 

Its branches of distribution " 500 



PART VI. 

SPLANCHNOLOGY. 

Division A. 

The heart, or organ of the circulation " 505 

Its general construction . . " 505 

Its cavities " 506 

Its valves " 509 

Its vessels and nerves " 512 

Its rings . . " 512 

The pericardium. , . " 512 

Division B. 

The organs of digestion , " 514 

The alimentary canal and its divisions " 514 

The accessory organs, table of " 514 

The mouth • ." 515 

The tonsils " 515 

The tongue " 516 

The salivary glands " 517 

Points of surgical interest " 517 



GENERAL INTRODUCTION. xiil 

The pharynx .... Page 518 

Its attachments and relations " 518 

Its openings " 518 

Its muscles * . • " 5 T 8 

Its mucous membrane " 519 

Its vessels and nerves " 519 

The (esophagus " 519 

Its relations. " 519 

Its coats , " 519 

Its vessels and nerves " 519 

The stomach " 520 

Its relations " 520 

Its coats " 520 

Its glands and mucous membrane " 521 

The intestinal canal " 521 

Its divisions " 521 

The duodenum " 522 

The jejunum " 522 

The ileum " 522 

The caecum .• " 522 

The colon " 523 

The rectum '• 523 

Structure of the intestine as a whole " 523 

Differences between the large and small intestine " 524 

The peritoneum " 525 

The mesentery " 525 

Its ligaments , " 526 

The omenta " 526 

The liver... " 527 

Its relations " 527 

% Its ligaments " 528 

Its fissures " 529 

Its lobes " 529 

Its vessels, " 53a 

Its ducts . " 531 

Its general structure " 532 

The pancreas " 533 

Its relations . " 533 

Its general structure " 533 

The spleen " 534 

Its relations " 534 

Its general structure " 535 

Its vessels " 535 

Division C. 

The regions of the abdomen " 535 

Boundaries of " 535 

Contents of , " 536 

Division D. 

The organ of phonation " 53*; 

The larynx «« 5 — 

Its cartilages •• 537 

Its ligaments " 542 

Its muscles " 539 

Its cavity and its points oi interest " 543 



XIV GENERAL INTRODUCTION. 

The larynx (continued). Page 

Its mucous membrane " 543 

Its vessels and nerves " 544 

Division E. 

Organs of respiration " 545 

The Trachea " 545 

Its situation " 545 

Its cartilages " 545 

Its muscular fibres " 545 

Its arteries and nerves " 545 

Its surgical aspects and relations " 546 

The Bronchi " 547 

Variations in the right and left " 547 

Relations of each " 547 

Rings of " 547 

Cartilage plates of " 547 

Distribution and course of " 548 

The Lungs " 548 

General appearance " 548 

Relations of special portions " 548 

Relations of important internal structures.. " 549 

The parenchyma and its structure " 550 

The cellular structure " 551 

The serous covering , " 552 

Its reflections " 552 

Its arteries. . .- " 553 

Its veins " 553 

Its nerves " 553 

The thyroid gland " 553 

Its intimate structure " 554 

Its vessels and nerves " 554 

THE THYMUS GLAND. ., " 554 

Its situation " 554 

Its relative size " 554 

Its intimate structure " 555 

Its vessels and nerves " 555 

Division F. 

The urinary organs " 555 

The Kidney " 555 

Its situation " 555 

Its external points of interest " 556 

Its relations. " 556 

Its intimate structure " 557 

Its vessels and nerves " 558 

The ureter , " 559 

Its subdivisions " 559 

Its structure " 559 

Its surgical relations " 559 

The bladder " 560 

Differences in the sexes " 560 

Alterations with age " 560 

Its relations " 560 

Its ligaments " 561 

Its coats " 5Q 2 



GENERAL INTRODUCTION. XV 

The bladder (continued) Page 

Its cavity and its points of interest " 562 

Its vessels and nerves " 563 

Division G. 

Male genital organs " 563 

The penis " 563 

Its structure " 563 

Its erectile tissue " 564 

Its vessels and nerves ., " 565 

The urethral canal " 565 

Its subdivisions and the points of interest of each " 595 

Its coats " 566 

Its glands " 567 

Its vessels and nerves " 567 

The testicle " 567 

Its situation " 567 

Its coverings " 568 

Its intimate structure * 568 

Its duct " 569 

Its vessels and nerves. " 569 

The prostate gland 4< 570 

Its situation. . . . .' " 570 

Its variations in size " 570 

•Its lobes " 570 

Its vessels and nerves " 570 

Its surgical importance " 570 

The spermatic cord « 571 

Its situation " 571 

Its structure " 571 

Its vessels and nerves " '571 

Division H. 

Female genital organs " 572 

The external organs « 572 

Mons veneris " 572 

Labia majora " 572 

Nymphae " 572 

Clitoris " 572 

Vestibule " 572 

Hymen " 572 

The internal organs " 573 

The vagina " 573 

Its structure " 573 

Its vessels and nerves " 573 

The uterus . 

Its structure 

Its cavities « ' 5 74 

Its ligaments " 575 

Its coats " 575 

Its vessels and nerves " 576 

Appendages to uterus « 576 

Fallopian tubes " 576 

The ovaries •« 576 

Intimate structure of. " 576 

Coats of. " 576 



574 

574 



xvi GENERAL INTRODUCTION. 

The ovaries (contiuued) Page 

Vessels and nerves of " " 577 

Division I. 

Organs of sight " 578 

The eye " 57S 

Its coats or tunics " 573 

Its refracting media " 578 

Its intimate structure " 578 

Its appendages " 582 

The eye-brows, " 582 

The eye-lids " 582 

The lachrymal apparatus " 583 

The lachrymal canals " 583 

The lachrymal sac " 583 

The nasal duct . , " 584 

The tendo-oculi. . . ., " 584 

Division J. 

The organs of hearing " 584 

The external ear " 584 

The pinna and its component parts . . . . " 584 

The external auditory canal " 585 

The middle ear or tympanum . " 586 

Its boundaries " 5S6 

Its bones " 587 

Its muscles.. " 589 

Its openings " ggo 

Its vessels and nerves. 

Its function 

The internal ear or labyrinth , " 50,0 

Its general form " 591 

Its fluids " 

Its scalae and their formation " 

Its membranous structure " 

Subdivisions of " 

Its vessels and nerves " 50,5 

Mechanism of hearing " 5g6 

Division K. 

The perineum of the male " 50,7 

Its boundaries " 597 

Its general outline " 597 

Its component parts " 597 

Its fasciae " 598 

Its arteries and nerves. ......; " 600 

Parts divided in lithotomy " 601 

The perineum of the female " 602 

Its boundaries " 602 

Its analogy to that of the male . „ „ . " 602 

Its points of difference " 602 

Its functions and important surgical bearings " 602 



590 
590 



591 
593 

595 
595 



/ 



THE ESSENTIALS OF ANATOMY. 



GENERAL INTRODUCTION. 



The term Anatomy comprises that department of science, 
which treats of the structure of organized bodies. 

Anatomy may be divided into two great classes, Phytotomy, or 
vegetable anatomy and Zootomy, or animal anatomy. 

The following table exhibits some of the more important 
divisions of Anatomy which will subsequently merit a special 
description. 



ANATOMY 
(2 great 
classes) 



Phytotomy or Vegetable Anatomy. 



* Comparative 

Anatomy. 



Zootomy 

or Animal - 
Anatomy. 



Special 

Anatomy. 



'Histology, or General Anatomy. 
Morphology or Descriptive Anatomy. 
.Relative or Surgical Anatomy. 



These varieties may be thus defined : 

" Comparative Anatomy " is that department of science which 
treats of the organs in one animal as compared with those in an- 
other. 

" Special Anatomy " treats of the anatomy of Species or of 
parts of the whole structure. It includes Histology, Morphology 
and Relative or Surgical Anatomy. 

" Histology " treats of the intimate structure of organs or 
tissues. 

" Morphology," or " Descriptive Anatomy," treats of the 
name, form, size and situation of the various structures. 

" Relative," or " Surgical Anatomy," treats of portions of 
Special Anatomy with reference to its surgical interest and value. 

Various other terms are often applied to special departments 
of Anatomy with reference to the standpoint, from which anatomi- 
cal researches are considered or made. Among these special 
varieties may be enumerated : 



GENERAL INTRODUCTION. 

(i.) "Philosophical Anatomy." — A treatise on the mode or 

or plan on which tissues are 
formed. 

(2.) "Transcendental Anatomy." — The same as the Philoso- 
phical. 

(3.) " Topographical Anatomy." — The anatomy of regions as 

a separate division of study. 

(4.) " Microscopical Anatomy." — The study of magnified 

tissues. 

(5.) " Pathological Anatomy." — The study of tissues in dis- 
ease as revealed by inspection 
and examination. 

(6.) " Morbid Anatomy." — The study of the changes of tis- 
sues in disease and the ex- 
planation of the same. 

(7.) " Forensic Anatomy." — The science of morbid anatomy 

when applied to medical ju- 
risprudence. 

(8.) " Veterinary Anatomy." — The study of the anatomical 

structure of the domestic 
animals. 



ANATOMY OF MAN. 
In the following diagrammatic illustration, are represented all 
the various parts of the human frame work, which demand the 
attention of the student of Anatomy. 



Fluids. 



Solids. 




GENERAL INTRODUCTION. 3 

In this diagram we see that the main anatomical elements of 
the body are divided into the solid and the fluid elements. The 
fluid elements are placed upon the left hand, while the solid ele- 
ments are arranged upon the right hand side of the page. 

The two main divisions given off from the central unit or man, 
are named respectively, hygrology, or the doctrine of the fluid 
elements, and stereology, or the doctrine of the solid elements. 

STEREOLOGY is subdivided into sarcology, or the doctrine per- 
taining to the softer tissues of the body, and skeletology, or the 
doctrine of the bony framework of the body. 

SARCOLOGY is shown to include, (i) myology, or the doctrine 
of the anatomy of the muscular system. (2) neurology, or the 
doctrine of the anatomy of the nervous system. (3) splanchno- 
logy* or the doctrine of the anatomy of the internal viscera. (4) 
angiology, or the doctrine of vessels. (5) adenology t or the doctrine 
of glandular structures. (6) dermatology, or the doctrine of the 
skin, and (7) genesiology, or the doctrine of the generative organs. 

SKELETOLOGY is shown to include both syndesmology, or the 
doctrine of the anatomy of the joints, and osteology, or the doc- 
trine of the anatomy of the special bones. 

FLUIDS. 

The fluids of the body are divided also in this diagrammatic 
chart into, (1) The formative, which include the lymph and chyle, 
(2) The Blood or permanent fluid, and (3) The secretive, which 
comprise the recrementitious fluids, which are appropriated by the 
body, and the excrementitious fluids, which are cast off as unfit 
for nutritive processes. 

Each of these respective heads will be treated of in this vol- 
ume, and the description of the various points of anatomical in- 
terest, pertaining to each, will be so tabulated and arranged, as to 
afford, to the student, the greatest possible help in the acquisition 
of accurate and practical anatomical knowledge. All points in 
Anatomy, which are as yet matters of doubt, will be purposely 
either omitted or left in question, since it is the desire and inten- 
tion of the Authors to publish a volume containing only anatomi- 
cal facts rather than to enter upon speculative ground. 



OSTEOLOGY 



OSTEOLOGY. 



THE SKELETON. 



The bones forming the human skeleton are two hundred in 
number, and may be thus classified : 



(i) Bones of the Head, 

(2) " " Trunk, 

(3) " " Extremities, 

(4) The HYOID ARCH, 



The 22 bones of the Head consist of 



22 

53 

64 

.60 

1 
Total 200 



. (4 mesial. 

( Cranium 8 "J 2 pairs. 



( Face 14 \ 
Total, 22 



2 mesial. 
6 pairs. 



The 53 bones of the Trunk consist of 



'Vertebrae 24 
Thorax 25 

Pelvis 4 

Total 53 



Ribs (12 Pairs.) 
Sternum (1 Bone) 

( 2 mesial. 

\ 1 pair. 



The 64 bones in both Upper Extremities are - 



Shoulder, J » 



Arm 
Forearm 



Hand 



1 -{ Humerus, 
j Radius. 

2 ( Ulna. 

8 in Carpus. 



5 " Metacarpus. 
14 Phalanges. 
Total 32 (on each side.) 



The 60 bones in both Lower Extremities are 



-Thigh 
Leg 

Foot 
Total 



i~{ Femur. 

( Patella. 

2 S Fibula. 

( Tibia. 
7 in Tarsus. 
5 in Metatarsus 
14 Phalanges. 
30 (on each side.) 



In this classification of the bones of the human body, the fol- 
lowing structures, which by some Anatomists have been enumer- 
ated as individual bones, have been purposely excluded: 

(1) Ossa Triquetra (Wormian bones.) 

(2) The bones of the middle Ear. 

(3) Sesamoid bones. 

(4) The Teeth. 



8 



THE SKELETON. 



The bones of the human body may be classified in the second 
place, in respect to their shape, as follows : 



f Clavicles 2 

3 of Upper Extremity of each side 6 

Metacarpal bones io 

(90) ^ 3 of Lower Extremity of each side 6 

Metatarsal bones IO 

Phalanges (of hands and feet) 56 

Total, 90 

( Carpal of both sides 16 

(30) -J Tarsal " " 14 



Bones of the Hu- 
man Body. 
(classified as to their) 
shape. 



Long bones 



Short bones 



Flat bones 



(40) i 



Irregular bones (40) 



Total, 200 



Total, 30 

! Occipital. 
Frontal 4 
2 Parietal. 
{2 Nasal. 
2 Lachrymal 5 
Vomer. 

Scapula 2 

Sternum 1 

Ribs 24 

Os Innominatum 2 

Patella 2 

Total, 40 

{Vertebrae, 24"] 
Sacrum, iL. 26 
Coccyx 1 J 
( 2 Temporal, 

Of the Skull \ Ethmoid 4 

( Sphenoid. 

(2 Superior Maxillary, 
2 Malar, 
Of* the Face -I 2 Palate, 9 

I 2 Inferior turbinated 
(_ Inferior Maxillary. 
Hyoid Bone " . 1 

Total, 40 



The LONG BONES are used as means of support to the other 
portions of the skeleton, or as levers upon which the muscular 
system can act to the best advantage. 

The SHORT BONES are situated where great solidity, a limited 
amount of motion, and compactness are required. 

The FLAT BONES are important agents in the protection of the 
organs, contained within the various cavities of the body, as in 
the cranium, thorax, and pelvis, and from their shape they serve 
to give extensive attachment to muscles. 

The following table will serve to show the regions of the body 
where each of these four varieties of bones predominates. 



CLASSIFICATION OF BONES. <• 

Table illustrating the Position of the Bones of the Human Skeleton 
when classified according to their shape. 





Head. 


Trunk. 


Extremities. 


Hyoid Arch. 




Bones. 


Cranium. 


Face. 


Vertebral 
column. 


Thorax. 


Pelvis. 


Upper. 


Lower. 




Total. 


Long. 
Short. 
Flat. 
Mixed. 


4 
4 


5 
9 


24 


25 


2 

2 


46 
16 

2 


44 
14 

2 


I 


90 
30 
40 
40 




8 


14 


24 


25 


4 


64 


60 


I 


200 




22 


53 


124 


I 





The bones of the human skeleton may, in the third place, be 
divided for convenience of description into single or mesial bones, 
and into pairs of bones, as in following table : 



Bones of Human 
Skeleton classi- 
fied in reference to 
the mesial line of 
the body.) 



Mesial or Single 
Bones (34.) 



L Pairs of Bones (83) 



f Occipital 1 
In cranium §*£$ ' 

I Frontal J 

j Vomer 

( Lower jaw- 
Vertebrae 24 

In ***■ \ c"^ \ * 

Sternum r 

Hyoid bone 1 

Total, 34. 



In face. 



34 



'Superior maxillary, 
Nasal, 
A lachrymal, 
Malar, 
Palate. 
__ Inferior turbinated, 

In upper extremity 32 

In lower " 30 

In pelvis 1 

In trunk (ribs) 12 

Total, 83x2=166 

Total, 200 



Bony Prominences and Depressions. 

Upon almost every bone in the human skeleton are to be seen 
various prominences and depressions. These prominences and 
depressions, although they may often appear to the student but 
trivial and possibly accidental in their character, are nevertheless 
important, and each one is usually designated with some special 
name, which is supposed to indicate either its location, its general 



10 



BONY PROMINENCES. 



character, or the particular function which it is destined to per- 
form. From such a basis of nomenclature, however, the variations 
in names have become almost beyond the reach of a student's 
memory, unless the meaning of the more common forms be point- 
ed out and the student be assisted, by some classification, to grasp 
the general principles upon which these names have originally been 
applied. For this purpose then, the following tables are appended : 



Names applied to Promi- 
nences on Bones. 



Bony Prom- 
inences. 



(I) For the pur- 
poses of ar- 
ticulation. 



In movable joints, j Condyies. 

{Dentations. 
Ridges. 
Roots. 



(II.) For the in- 
sertion of fibres. 



(i) Names given 
from the general 
form, viz. : 



r Tubercle (if small and uneven.) 

Impressions. 

Lines (if narrow and pro- 
longed.) 

Crests. 

Spines (if slender and pointed.) 

Prominences. 

Tuberosities (if broad, rough 
and uneven.) 

'Azygos (without a fellow.) 

Clinoid (a bed.) 

Coracoid (a crow's beak.) 

Coronoid (the top of a curve.) 

Hamular (a hook.) 

Malleolar (a little mallet.) 

Mastoid (a nipple.) 

Odontoid (a tooth.) 

Pterygoid (a wing.) 

Rostrum (a beak.) 

Spinous (a thorn.) 
w Styloid (a pen.) 



f Articular. 
(3) Names given! Orbital, 
from their use, viz : 1 Trochanteric (to turn.) 
[Zygomatic (to join.) 



(2) Names given 
from their resem- 
blances, viz. : 



(4) Names given 
from their direc- 
tion, viz. : 



f Ascending. 
J Descending. 
1 Transverse. 

[ Oblique. 



(III.) For the reflection of tendons — as Malleoli, Hamular processes, etc. 



DEPRESSIONS IN BONES. 



II 



Names applied to Cavities 
in Bones. 



Cavities in 
Bones. 



Articular. 



r Cotyloid (cup shaped.) 
Glenoid (shallow.) 
Trochlea (like a pulley.) 
Facet (smooth.) 
Alveolar. 
Acetabulum. 

(i) For reception and (Fossae. 
protection. \ Sinuses. 



(2) For insertion. 



I Temporal, 
•j Zygomatic. 
( Pterygoid. 



Non Ar- 
ticular. 



1 Aqueducts, 
Foramina. 
Canals. 
Fissures. 
Notches. 

(4) To increase the sur- (Cells (as in Ethmoid bone.)" 
face of the bone. \ Sinuses (as in Frontal bone.) 



(5) To deflect tendons. \ 



Sciatic notches. 
Bicipital groove. 



(6) rgtoMri** pS r M MeduIlai ?- 

( Periosteal or capillary foramina. 
k (7) Depressions for glands or arteries. 

When a projection from the surface of a bone is connected to 
it by cartilage, it is termed an Epiphysis ; when, by the process 
of ossification, the cartilage disappears and it becomes united by 
bone, it is called an Apophysis. 

The shaft of a long bone is often called its Diaphysis. 

Minute Anatomy of Bone. 
If a transverse section of bone tissue be rendered sufficiently 
thin to allow of a microscopical examination by transmitted light, 
it will be found to present for inspection the following points of 
interest, which have been separately named and which enter 
prominently into its construction : 

1. Haversian Canals. 

These canals have an average diameter of about -^ of 
an inch, and are round, oval, or angular in their form. 
They contain arterial vessels, and, in the larger ones, 
veins are frequently present. 

2. Canaliculi. 

These small canals vary in size from tt! tit to 20000 °f an 
inch in diameter and serve to connect the Haversian 
canal with spaces in the bone called lacunae. 



12 MINUTE ANATOMY OF BONE. 

• 

3. Lacunce. 

These are seen as irregular dark spaces, which may be 
noticed to have a general circular arrangement around 
the Haversian canal. They contain the bone cell. 

4. Haversian Spaces. 

These are larger and irregular-shaped spaces which con- 
nect the Haversian canals with the medullary spaces of 
cancellous bone tissue. They are found in young and in 
growing bones more extensively than in adult life. 

5. Concentric Lamellce. 

These are layers of bone tissue which are arranged 
around an Haversian canal as an axis. They enclose 
within their substance the lacunae of bone. 

6. Circumferential Lamella. 

These are layers of bone which serve to unite or bind 
together the various Haversian canals and their concen- 
tric lamellae. 

7. Interstitial Lamellce. 

These are layers of bone tissue which are woven in and 
out between the concentric lamellae surrounding the 
various Haversian canals. 
Each Haversian canal, if taken in connection with its numerous 
investing or concentric lamellae, is termed an Haversian System 

The vessels of bone consist of arteries, veins and lymphatics, 
although the latter have been denied by some of the more promi- 
nent observers. 

The arteries of bone are of three orders, as follows : 

1. Nutrient Artery, which enters at the nutrient foramen and 

distributes branches along the entire length of the 
medullary canal of the bone. 

2. Articular Vessels, which chiefly nourish the cancellous tis- 

sue of bone. 

3. Periosteal Vessels, which ramify in the periosteum and 

which supply the compact tissue of bone with blood. 
The veins of bone, especially the long bone, emerge also in 
three distinct localities as follows : 

1. By a large vein which accompanies the nutrient artery. 

2. By numerous large and small veins, which emerge from the 

articular ends of the bone. 

3. By many small veins which escape from the compact tissue 

along the length of the shaft. 



GENERAL OSTEOLOGY. 



Composition of Bone. 



13 



With the exception of the teeth, bone is the hardest structure 
of the human body, and is composed of two distinct elements, 
viz., the Organic or Animal constituents, and the Inorganic or 
Mineral constituents. The organic elements of bone may be 
most clearly demonstrated by subjecting a bone to the prolonged 
action of a diluted solution of nitric or muriatic acid, when the 
mineral ingredients will be found to have been dissolved, and the 
bone, although still retaining its original bulk and form, will pre- 
sent a degree of flexibility, which will admit of its being tied into 
a knot without danger of fracture. 

On the other hand, if a bone be subjected to extreme heat 
the animal ingredients will be consumed and the bone will then 
be found to be extremely brittle and to be greatly decreased in 
its weight. 

The organic constituents of bone form about one-third of the 
entire bone, and the inorganic constituents the remaining two- 
thirds. 

The various substances, revealed by a chemical analysis of the 
organic and inorganic constituents found in bone, are shown in 
the following table : 



Organic matter, Gelatin and bloodvessels and fat 33.30 

'Phosphate of lime 51.04 

Carbonate of lime. . „ n.30 

Fluoride of calcium 2.00 

Phosphate of magnesia 1.16 

Soda and Chloride of Sodium. . 1.20 



Inorganic or earthy matter 



The relative proportions between the organic and the inor- 
ganic elements of bone differ in the various portions of the skele- 
ton, and also at different periods in life. 

Thus the bones of the head and the long bones in the ex- 
tremities contain more earthy matter than the bones of the 
trunk. The bones of the upper extremity also contain more than 
the corresponding bones of the lower extremity. The humerus 
contains a greater proportion of inorganic matter than the radius 
or the ulna, and the femur more than the tibia and the fibula. 
The metacarpal and metatarsal bones are only slightly richer in 
earthy matter than the bones of the trunk. 

As age advances, the mineral elements of bone tend to in- 
crease. This is most especially marked in the long bones of 
the extremities and in the bones of the head ; both of which 
localities in fcetal life seem to be deficient in earthy salts as com- 



14 



THE SKELETON. 



pared with the proportion present during adult life. In the 
bones of the trunk of the adult, on the contrary, no change 
from the fcetal proportions between the organic and the in- 
organic bone ingredients occurs. 

The relative proportion existing between the earthy and 
mineral ingredients of bone exerts a marked influence on the 
development of the figure and on the rapidity of repair in case 
of fracture. Thus the bones become bent and twisted, when an 
excess of organic material is present, while a marked tendency 
to fracture is produced by a deficiency in those elements. In 
rickets, the former condition is usually present from some error 
in nutrition, while, in old age, the latter condition is liable to be 
developed. 



BONES OF THE HEAD 



CSTEOLOGY OF THE HEAD. 1 7 

OSTEOLOGY OF THE HEAD. 
The head is composed of two great divisions, viz. : 
A. The Cranium, composed of 8 bones 



Total 22 bones. 
B. The Face. composed of 14 bones 

The 8 bones entering into the formation of the cranium may 

be subdivided into 4 single or mesial bones and 2 pairs of bones, 

as is represented in the following tabular arrangement : 

f Occipital. 
f Mesial or Single Bones (4) \ g™™' 



I Frontal. 
[. < 



i Temporal. 



Bones of the Cranium. 

[Fairs of Bones (2) | £££££ 

Total 8 

The mesial or single bones are enumerated in this table in their 
order from behind forward and may be remembered by the initial 
letter of each, O. S. E. F., which bear some resemblance to the 
old method of spelling Joseph. As explained in the introductory 
pages upon osteology, these bones, like all mesial bones, lie in 
the median plane of the body and articulate upon either side with 
pairs of bones. It will thus be understood that when pairs of 
bones are spoken of, that one lies upon the right and one upon 
the left of the median plane of the body. 

The mesial bones are also often called symmetrical bones, 
since they are capable of being divided into two similar parts. 

In describing the bones of the cranium certain words will be 
encountered by the reader, the meaning of which deserve to be 
clearly understood before entering into the study of osteology. 

In anatomy the words external and internal are used to ex- 
press the relation of a bone or any separate structure, as a whole, 
to the mesial plane of the body. 

The words exterior and interior, when applied to a bone, are 
used to express the relation of the surfaces to the centre of the 
cavity which it contributes to form. This applies particularly to 
the skeleton of the cranium, thorax and pelvis. 

The words anterior and posterior, indicate the relation of any 
part to the ventral or dorsal plane of the body. 

The words superior and inferior, express the relation of any 
part to the central point of the body. 

The word beneath is applied to parts more distant from the 
surface. 

It must be constantly borne in mind that the words superior,, 
inferior, anterior, posterior, above and below, have reference to 



1 8 BONES OF THE HEAD. 

the position of the parts in the erect posture of the body, and the 
neglect of this caution has tended, in no small degree, to em- 
barrass the student, and to render description otherwise full and 
complete, almost unintelligible. 

THE OCCIPITAL BONE. 

This bone is situated in the posterior and inferior part of the 
cranium. In form, it is classed among the flat bones. Its direc- 
tion is both horizontal and vertical, since it enters into the forma- 
tion both of the base of the skull and the posterior portion of the 
cranium. 

The occipital bone presents for special consideration the fol- 
lowing component parts : 

An outer surface. 
An inner surface. 

Four borders \ ff™*® 
( Inferior (2.) 

{Lateral (2.) 
Superior (1.) 
Inferior (1.) 

Outer Surface. 

This portion of the occipital bone is convex in shape, and 
possesses several points of anatomical interest which may be thus 
described : 

(1.) A projection called the occipital protuberance for the in- 
sertion of the ligamentum nuchse. 

(2.) A bony ridge running from the occipital protuberance to 
the foramen magnum, and called the occipital crest. 

(3.) Two curved lines called the superior and inferior curved 
lines of the occipital bone. The superior affords at- 
tachment to the occipito-frontalis, sterno-mastoid and 
trapezius muscles. The inferior gives attachment to 
the rectus capitis posticus major and minor muscles. 

(4.) A space between the two curved lines, from which arise the 
complexus, splenius capitis and the superior oblique 
muscles. 

(5.) The foramen magnum, through which pass the spinal cord 
and its membranes, the spinal accessory nerves and 
the vertebral arteries. 

(6.) The condyles of the occipital bone, which are oblong in 
shape, converging in front, looking downwards, for- 
wards and outwards, and which are roughened on their 
inner aspect for the insertion of the check ligaments. 
They articulate with the cups of the atlas. 



OCCIPITAL BONE, 1 9 

(7.) The anterior condyloid foramina, which are situated in 
front of the condyles and which transmit the hypog- 
lossal nerves. 

(8.) The posterior condyloid foramina, which lie behind the 
condyles and which transmit a vein to the lateral sinus 
of the skull. Occasionally no foramen is present and 
a fossa takes its place. 

(9.) The jugular processes, which lie on the outer side of the 
condyle and which give attachment to the recti cap- 
itis laterales muscles and to the lateral occipito-atloid 
ligaments. 

(10.) The basilar process, which forms the anterior projection 
of the occipital bone and which articulates with the 
body of the sphenoid bone. 

(11.) The pharyngeal spine, which is a bony projection upon 
the basilar process for the attachment of the tendin- 
ous raphe and the superior constrictor muscle of the 
pharynx. 

(12.) Two rough depressions upon the basilar process for the 
recti capitis antici majores and minores muscles. 

Inner Surface. 

The inner surface of the occipital bone is concave in its shape 
and is divided into four fosses by two crucial ridges of bone, which 
at their point of intersection form the internal occipital protuber- 
ance, at the centre of which is a depression which corresponds to 
the torcular Herophili. The upper division of this crucial ridge 
of bone ascends to the superior angle of the occipital bone, and 
is deeply grooved for the superior longitudinal sinus and for the 
attachment of the falx cerebri. 

The inferior division is termed by some anatomists the inter- 
nal occipital crest. It descends to the foramen magnum where it 
bifurcates. It gives attachment to the falx cerebelli. 

The lateral divisions of this crucial ridge form the inferior 
boundaries of the two superior or cerebral fossae, and the superior 
boundary of the inferior or cerebellar fossae of the occipital bone. 
They are deeply grooved for the attachment of the lateral sinuses 
and the tentorium cerebelli. 

At the lower portion of the bone upon its inner surface, is seen 
again the internal margin of the foramen magnum, which has 
already been described, and, near the sides of this large opening, 
appear also the internal orifice of the anterior condyloid foramina. 
Upon the internal surface of the basilar process is seen the basilar 



20 BONES OF THE HEAD. 

groove, in which lie the pons Varolii and the medulla oblongata, 
and, upon each side of the basilar groove, are two smaller grooves 
which partly lodge the inferior petrosal sinuses. 

Borders. 

The occipital bone presents for examination two superior 
borders and two inferior borders. 

The superior borders articulate with the parietal bone of each 
side of the cranium, and by so doing form the lambdoidal suture. 

The inferior borders articulate with the mastoid and petrous 
portions of the temporal bone and assist in forming the jugular 
foramen or the foramen lacerum posterius. 
Angles. 

The occipital bone has four angles, the superior, the inferior, 
and two lateral angles. 

The superior angle is formed by the approximation and union 
of the two superior borders of the bone. It is received between 
the two parietal bones of the skull and assists in forming the so- 
called posterior fontanelle, which is a triangular space bounded on 
either side by the parietal bones and behind by the occipital bone 
and which is uncovered by bone at the time of birth. 

The inferior angle is situated at the end of the basilar process 
of the occipital bone and joins with the body of the sphenoid 
bone, to which it becomes ossified at about the eighteenth or 
twentieth year of age. 

The lateral angles are received between the posterior inferior 
angles of the parietal bone and the mastoid portions of the tem- 
poral bones. It presents upon its inner surfaces a portion of the 
grooves for the attachment of the lateral sinuses. 

Muscles attached to the Occipital Bone. 

To the occipital bone are attached twelve pairs of muscles, all 
of which arise from its exterior surface. 

These twelve pairs of muscles may be thus classified : 

( OCCIPITO-FRONTALIS. 

' To superior curved line (3) ■< Trapezius. 

( Sternocleidomastoid. 

Between the curved lines (2) jgEJScUm 

Between the inferior . ( Obliquus Capitis superior. 
curved line and for- (3) •< Rectus Capitis posticus major. 
amen magnum / Rectus Capitis posticus minor. 

( Superior constrictor of pharynx. 
To basilar process (3) < Rectus Capitis Anticus Major. 
( Rectus Capitis Anticus Minor. 
To jugular process (i)-{ Rectus Capitis lateralis. 

Total 12 



Muscles at- 
tached to Oc- 
cipital bone. 
(12.) 



SPHENOID BONE. 21 

The foramina in the occipital bone vary from three to five in 
number since three are constant and two are variable. 

The two posterior condyloid foramina are often absent, but the 
two anterior condyloid foramina and the foramen magnum are 
constant both in their location and in the structures which they 
transmit. 

Articulation of the Occipital Bone. 

The occipital bone articulates with six bones of tne skull, 
which may be enumerated as follows : 



Articulations of the 
Occipital bone/ 



! Atlas. 
Sphenoid. 

fThe Temporal bones. 
The Parietal bones. 
Total 6 

Development of the Occipital Bone. 

The occipital bone has four centres of development : one for 
the posterior or the occipital portion, one for each condyle, and 
one for the basilar process of the bone. At birth the bone con- 
sists of four separate parts as indicated by the location of the cen- 
tres of ossification. At about the fourth year, the two condyloid 
portions join with the occipital portion, and two years later the 
basilar process becomes joined, thus completing the entire bone. 

THE SPHENOID BONE. 

The sphenoid bone is situated at the anterior portion of the 
base of the skull and is wedged in between the other bones of the 
cranium. In shape it resembles a bat with its wings outstretched. 

It possesses 12 foramina, 12 pairs of muscles, 10 points of 
ossification, and it articulates with 12 bones. 

The sphenoid bone enters into the formation of the following 
important anatomical regions. 

( The cavity of the Cranium. 
A. Five cavities < " " " both Orbits. 

( " " " both Nasal fosses. 



B. Four fossa 



The temporal fossa. 
" zygomatic fossa 
41 spheno-maxillary fossa. 
" pterygoid fossa. 



The spheno-maxillary fissure. 
>terygo-ma 
phenoidal 



C. Three Jissuresl " pterygo-maxillary 



22 BONES OF THE HEAD. 

The sphenoid bone presents for examination the following 
component parts : 

(i.) A Body. 

(2.) Three greater processes. 

(3.) Eleven lesser processes. 

The 3 GREATER PROCESSES of the sphenoid bone are as fol- 
lows : 

(1.) The greater wings. 

(2.) The lesser wings or " Processes of Ingrassias." 

(3.) The pterygoid processes. 

The 1 1 LESSER PROCESSES of the sphenoid bone may be clas- 
sified as follows : 



Lesser processes of the J 



I Ethmoidal spine. 
Single processes (3) < Olivary process. 

( Rostrum or Azygos process. 



sphenoid bone. ] f The two posterior clinoid processes. 

\ n ■ r /0 \ ) The two anterior clinoid processes. 

[4 Pairs of processes (8) j The twQ middle dinoid ? \ ocess ^ 

{_ The two spinous processes. 
Total 11 

Some of these smaller processes will be found described under 
the description of the body and the greater processes of the bone, 
since they exist either as parts of those larger projections or as 
prominent points upon the central body of the sphenoid. 

Body of Sphenoid. 

The body of the sphenoid bone is cuboid in its shape, but it 
presents only four free surfaces instead of six, since the two lateral 
surfaces are continuous with and afford attachment to the greater 
and the lesser wings and the pterygoid processes of the bone. 

Upper Surface. 

The upper surface of the body is situated in the interior portion 
of the cranium. It presents, from before backwards, the following 
points deserving of special mention. 

(1.) The ethmoidal spine, which articulates with, the ethmoid 
bone, and which consists of a horizontal projection, of 
a pointed shape, from the anterior edge of the body of 
the sphenoid. 
(2.) A smooth surface just behind the ethmoidal spine marked 
by two shallow grooves for the support of the olfac- 
tory nerves. 
(3.) The optic groove, which supports the commissure of the 
optic nerves and which leads, upon either side, to- 
wards the optic foramen. 



SPHENOID BONE. 23 

(4.) The olivary process, just behind the optic groove, and in 
front of the sella turcica. 

(5.) The pituitary fossa or sella turcica, so called since it 
lodges the pituitary body of the brain, and from its re- 
semblance to a turkish saddle. This fossa is bounded 
in front by the middle clinoid processes, and the cir- 
cular sinus of the brain is situated within it. 

(6.) Dorsum sellce, or the back of the saddle. This portion of 
the bone is grooved or notched at the sides for the 
passage of the 6th pair of cranial nerves, and at its 
superior angles it gives off the two posterior clinoid 
process for the attachment of the tentorium cerebelli. 

(7.) The cavernous groove, which is perceived upon each side 
of the body and which is curved like the letter S. 
This groove lodges the internal carotid artery and the 
cavernous sinus. 

Anterior Surface. 

The anterior surface of the body of the sphenoid bone has 
a direction which is nearly vertical. It presents for examination 
the following points of anatomical interest and importance : 

(1.) The sphenoidal crest. 

This portion of the bone articulates with the perpen- 
dicular plate of the ethmoid bone. 

(2.) The openings into the sphenoidal sinuses. 

These openings extend into the body of the bone, ren- 
dering it hollow and greatly decreasing the weight of 
the bone, in proportion to the surface which it presents. 

(3.) The sphenoidal turbinated bo?ies, or " Bones of Bertin." 

These bones partially close the openings of the sphen- 
oidal sinuses and articulate with the os planum of the 
ethmoid ; upon their sides and at their inferior por- 
tion, they articulate with the orbital processes of the 
palate bones. 

Under Surface. 

This surface of the bone enters into the formation of the nasal 
fossae. It presents for examination the following points of in- 
terest : 

(1.) The rostrum of the sphenoid. 

This thin plate of bone is received into a correspond- 
ing slit-like depression in the vomer between its two 
alas. It is, in reality, but a continuation downwards 
of the sphenoidal crest. 



24 



BONES OF THE HEAD. 



(2.) The vaginal processes. 

These processes of bone are situated on each side of the 
rostrum. They articulate with the alae of the vomer. 
(3.) The pterygopalatine grooves. 

These grooves are situated externally to the vagina] 
processes of the sphenoid. They form, by their articu- 
lation with the sphenoidal processes of the palate 
bones, the so-called pterygo -palatine canals, w r hich 
transmit the pterygopalatine artery and the pterygo- 
palatine nerves. 
Posterior Surface. 

This surface of the body of the sphenoid bone articulates with 
the basilar process of the occipital bone, and becomes ossified to 
it at the age of eighteen or twenty. It is quadrilateral in form. 

Greater Wings of the Sphenoid. 

The greater wings of the sphenoid bone are large irregular 
shaped masses which can only be thoroughly described by division 
into the following parts : 

(1.) A superior or cerebral surface. 

(2.) An external surface. 

(3.) An anterior or orbital surface. 

(4.) A circumference. 
The superior or cerebral surface, forms a part of the middle 
fossa at the base of the skull. It presents for examination four 
foramina, which allow of the exit of nerves from, or the entrance 
of vessels to the cavity of the cranium. These foramina may be 
thus enumerated from before backwards : 

(1.) The fora?nen rotundum which transmits^ Superior maxillary nerve. 

{Inferior maxillary nerve. 
Small petrosal nerve. 
Small meningeal artery. 
(3.) The foramen Vesalii " " -( A small vein. 

(4.) The foramen spinosum " " \ Middle meningeal artery. 

The external surface of the greater wing of the sphenoid bone 
is divided by a bony ridge called the pterygoid ridge into a su- 
perior and an inferior portion. 

The superior portion assists in the formation of* the temporal 

fossa. 
The inferior portion assists in forming the zygomatic fossa, 
and at its posterior portion it presents a bony promin- 
ence, called the spine of tJie sphenoid, which affords at- 
tachment for the internal lateral ligament of the jaw 
and also for the laxator tympani muscle. 



SPHENOID BONE. 2$ 

The anterior or orbital surface of the greater wing of the 
sphenoid bone is quadrilateral in shape. It assists in forming the 
outer wall of the orbit, and it also enters into the formation of 
the sphenoidal, and the spheno-maxillary fissures. It articulates 
with the frontal and the malar bones. It presents a small bony 
prominence, called its spine, to which is attached the lower head 
of the external rectus muscle. 

The circumference of the greater wing of the sphenoid bone 
serves the combined functions of articulation with other bones 
and the completion of foramina and fissures. 

From the back portion of the body of the sphenoid, as you 
progress towards the spine of its greater wing, the circumference 
of the wing assists in forming the anterior margin of the fora7nen 
lacerum medium, and it also articulates with the petrous portion 
of the temporal bone. 

From the spine of the greater wing to its tip, the circumference 
of the wing articulates with the squamous portion of the temporal 
bone. 

This articulating surface is bevelled upon its inner aspect, in 
the inferior portion of its length, and upon its outer or exterior 
aspect, in its upper or superior portion. 

From the tip of the greater wing to the front portion of the 
body, there exists a triangular surface for the articulation of that 
portion of the sphenoid with the frontal bone. The balance of 
this portion of the circumference of the wing forms the lower 
boundary of the sphenoidal fissure. 

Lesser Wings of Sphenoid. (Processes of Ingrassias.) 

These processes are long, thin, and of a triangular shape. 
They present for examination two surfaces, two borders, a base, 
and an apex. 

The upper surface is smooth, and forms a part of the anterior 
fossa, at the base of the skull. 

The under surface forms the back portion of the roof of the 
orbit and the upper boundary of the sphenoidal fissure, which 
transmits the 3rd, 4th, the opthalmic branch of the 5th, and the 
6th nerve, the opthalmic vein, a branch of the lachrymal artery, 
and a process of dura mater. 

The anterior border articulates with the frontal bone. 

The posterior borders form, at their inner extremities, the 
anterior clinoid processes. 

The base is connected to the body by two roots which by 



2 6 BONES OF THE HEAD. 

their separation enclose and form the optic foramen for the pass- 
age of the optic nerve and the opthalmic artery. 

Pterygoid Processes of the Sphenoid. 

These processes consist of two thin plates of bone, which are 
joined together anteriorly and which enclose between them the 
pterygoid fossa* These two plates, by their separation, form a 
triangular notch below, which articulates with the pterygoid 
process of the palate bone. 

The pterygoid processes present for examination an anterior 
and a posterior surface, and an internal and external pterygoid 
plate. The posterior surface constitutes the pterygoid fossa 
which gives origin to the external pterygoid muscle. 

The upper portion of the anterior surface forms the posterior 
wall of the spheno-maxillary fossa. It presents also the orifice 
of the Vidian canal, at about its point of junction with the body 
of the sphenoid bone. 

The external pterygoid plate is broad, thin, and inclined out- 
wards. It forms the inner wall of the zygomatic fossa, and the 
outer wall of the pterygoid fossa. It gives attachment to the 
internal and external pterygoid muscles. 

The internal pterygoid plate is long and narrow. Its outer 
surface forms the inner boundary of the pterygoid fossa, and its 
inner surface forms the outer boundary of the posterior nares. It 
presents at its apex the hamular process, which reflects the tendon 
of the tensor palati muscle, and, at its base, it presents the scaphoid 
fossa for the origin of the same muscle. 

Articulation of the Sphenoid Bone. 

The sphenoid bone articulates with 12 bones which may be 
thus classified : 



The Sphenoid bone 
articulates with 



Four single or Mesial bones. 



f Occipital. 
J Ethmoid. 

J Frontal. 

[ Vomer. 
j Temporal. 



!Two of Cranium j Parietal 
Two of the Face -j j£££ 



Of these twelve bones, all the remaining bones of the cranium 
comprise seven, and the remaining five are bones of the face. 

Foramina of the Sphenoid Bone. 

The sphenoid bone presents 12 formina, which are arranged in 
six pairs. These formina transmit five of the twelve pairs of 



SPHENOID BONE. 



27 



The sphenoid bone has | 5 Simple foramina, 
6 pairs of openings, <( 

viz. : 

1 1 Fissure, 



cranial nerves; viz., 2nd, 3rd, 4th, 5th, and 6th, and other struc- 
tures, as enumerated in the table of cranial foramina. 
These foramina may be thus classified : 

Optic foramen. 
Foramen rotundm. 

" ovale, 
Vesalii. 

" Spinosum. 

■{ Sphenoidal fissure. 

Each of these foramina has been alluded to in the descrip- 
tions of the various parts of the sphenoid bone. They will fur- 
thermore be found considered separately and in detail in " the 
classified table of foramina situated at the base of the skull." 

The sphenoid bone transmits two important arteries ; viz., the 
ophthalmic and the middle meningeal arteries, and contains one 
canal, called the Vidian canal, which transmits the Vidian nerve. 

Muscles attached to' the Sphenoid Bone. 

The sphenoid bone affords attachment to twelve pairs of 
muscles. These muscles may be thus classified : 

'Levator palpebrse. 
Superior oblique of the eye, 
Superior rectus " " 
Inferior " " " 

External " " " 

^Internal " " " 

i Temporal. 
External pterygoid. 
Interna] pterygoid. 

Muscles of deglutition, (2) \ % n V erior constrictor. 
to v ' ( 1 ensor palati. 

_ Muscle of the middle ear, (1) -J Laxator tympani. 
Total, 12 

Development of the Sphenoid. 

The sphenoid is developed by ten centres of ossification. 
These ten centres are distributed as follows : 

One for each greater wing (2) 
and external pterygoid 
plate. 

One for each internal pte>y- (2) 
goid plate. 

Two for foe posterior portion (2) 

of the body of the Sphenoid. 

Total, 6 
One for each lesser wing and 
the anterior part of die (2) 
body of the Sphenoid. 
One for each of the Sphe- (2) 
noidal turbinated bones. 



Muscles attached to 
Sphenoid Bone. 



the 



All the muscles of the Or- 
bit excepting the In- (7) 
erior oblique muscle. 



Centres of Ossifi- 
cation of the 
Sphenoid Bone, 



For the posterior half 
of the Bone. 



(6)1 



For the anterior half 
of die bone. 



(4) 



Total, 10 



Total, 4 



28 BONES OF THE HEAD. 

The process of ossification, between and in these separate 
pieces, takes place in the following order : 

The great wings and external pterygoid plates are first formed 
during the 2nd month of fcetal life. 

Each internal pterygoid plate is then formed, and becomes 
united to the external plate at about 4J months of fcetal life. 

The two centres for the development of the body of the bone 
are situated underneath the sella turcica. This portion of the 
bone ossifies after the middle of fcetal life, and is detached from 
the greater processes of the bone even at the time of birth. 

The lesser wings are formed by a separate centre for each. 
They become united at about the 8th month of fcetal life. 

Ossification begins in the sphenoidal turbinated bones at the 
end of the 3d year. 

At birth the sphenoid usually consists of the 5 following pieces : 
(1.) The body joined to the lesser wings. 
(2.) The 2 greater wings. 
(3.) The 2 pterygoid processes. 

The greater wings become united to the body during the first 
year, but the turbinated bones do not unite until the 10th or 12th 
year of age. 

THE ETHMOID BONE. 

This bone of the cranium is of a peculiarly light and spongy 
texture. It is cuboid in shape and projects downwards between 
the orbital plates of the frontal bone. It enters into the forma- 
tion of the orbital cavities and the nasal fossae. 

This bone serves five important functions in the structure of 
the skull and face. 

1st. It affords attachment to a strong fold of dura mater, 
called the falx cerebri or greater falx, which separates the two 
lateral halves of the brain, and which, by the separation of its two 
laminae, furnishes two channels for blood, termed the superior and 
the inferior longitudinal sinuses of the skull. 

2nd. It presents a number of small foramina for the trans- 
mission through its cribriform plate of the filaments of the olfac- 
tory nerves. 

3rd. It forms a large part of the septum which separates the 
two nasal cavities from each other. 

4th. It affords a large expanse of surface upon which the fila- 
ments of the olfactory nerves may be distributed. This portion 
of the bone comprises the so-called superior and middle turbinated 
bones. 



ETHMOID BONE. 



2 9 



5th. It affords a protective bony covering for the ethmoidal 
cells and at the same time it constitutes a large part of the inner 
walls of the two orbital cavities. This orbital portion of the 
bone is termed the " os planum" 

The ethmoid bone may be divided, for the convenience of 
description into the following three portions : 

(A.) The horizontal or cribriform plate. 
(B.) The perpendicular plate. 
(C.) The two lateral masses. 

Horizontal or Cribriform Plate. 

This portion of the ethmoid bone is received into the eth- 
moidal notch of the frontal bone. It forms the roof of the nose 
and a portion of the floor of the anterior fossa of the skull. It 
presents the following points of interest : 

(1.) The Crista galli process. 

This elevation of bone, so-called from its fancied resemblance 
to the comb of a cock, affords attachment to the anterior ex- 
tremity of the falx cerebri, and it also articulates with the frontal 
bone, thus completing the foramen ccecum. 

(2.) Three rows of minute foramina ; situated upon either side 
of the crista galli process. These foramina transmit the olfactory 
nerves. 

(3.) A fissure for the nasal branch of the ophthalmic nerve. 
This fissure is situated in the front portion of the cribriform plate. 

Perpendicular Plate. 

This portion of the ethmoid bone descends from the under sur- 
face of the cribriform plate and assists in forming the nasal septum. 

It is more or less inclined towards one side, in the large major- 
ity of subjects, and it presents numerous grooves for the protec- 
tion of the filaments of the olfactory nerves. 

The perpendicular plate of the ethmoid is of an irregular pen- 
tagonal form and has five borders, viz : an upper, an antero-supe- 
rior, an antero-inferior, a postero-superior, and a postero-inferior. 

The upper border is continuous with the crista galli. 

The antero-superior border articulates with the nasal bone. 

The antero-inferior border joins the cartilage of the nose. 

The postero-superior border articulates with the sphenoid. 

The postero-inferior border articulates with the vomer. 

Lateral Masses. 

These portions of the ethmoid bone are cuboid in their gen- 
eral form and enclose a large number of irregularly shaped cavities 



30 



BONES OF THE HEAD. 



called the ethmoid cells. These cells may be divided into an an- 
terior and a posterior set. 

The lateral masses of the ethmoid present for special examina- 
tion the following six surfaces. 

An anterior surface, 
A posterior surface, 
An upper surface, 
An outer surface, 
An inner surface, 
An under surface. 
The anterior surface presents broken cells which are rendered 
complete by the articulations of the lachrymal bone and the nasal 
process of the superior maxillary bone. 

The posterior surface, like the preceding surface, is character- 
ized by numerous half cells, which are rendered complete by the 
articulations of the sphenoidal turbinated bone and the orbital 
process of the palate bone. 

The upper surface of each lateral mass presents a number of 
. half cells which are rendered complete by the articulation of the 
ethmoidal notch of the frontal bone. Two grooves may also be 
here perceived which are rendered complete canals by articulation 
of the frontal bone, and are called the anterior and the posterior 
ethmoidal foramina. 

The under surface presents the projecting mass of bone termed 
the unciform process of the ethmoid. This process articulates 
with the inferior turbinated bone, and also assists in forming the 
inner wall of the antrum of Highmore. Upon this surface of the 
lateral mass of the ethmoid is also perceived, the inferior surface 
of the middle turbinated bone or process, as it is sometimes called. 
The inner surface of the lateral mass of the ethmoid forms 
part of the outer wall of the nasal fossae. It presents from above 
downwards the following parts which have been specially named, 
(i) The superior turbinated process or bone. 

This is small in its size, and consists of a thin lamella 
of bone which lies in the posterior part of the nasal 
fossa. 

(2) The superior meatus. 

This canal opens anteriorly and communicates with 
the posterior ethmoidal cells. 

(3) The middle turbinated process or bone. 

This consists of a convoluted plate of bone which ex- 
tends along the whole length of the lateral mass of the 
ethmoid. 



ETHMOID BONE. oj 

(4) The middle meatus. 

This canal within the nasal fossa, opens anteriorly and 

communicates with the anterior ethmoidal cells, and, 

by means of a wide funnel-shaped canal called the in- 

fundibulum, it also communicates subsequently with 

the frontal sinuses. 

The outer surface of the lateral masses of the ethmoid bone 

presents a smooth thin plate of bone which helps to form the 

inner wall of the orbit, and which is called the os planum. 

The os planum articulates with the following bones within the 
cavity of the orbit. 

fin front — with the Lachrymal bone, 
Articulation of the Os I Above " " Orbital plate of the Frontal bone. 

Planum of the Ethmoid^ Behind " " body of the Sphenoid, 
bone. I "R 1 it u \ Superior maxillary bone. 

I e OW ( Orbital process of the Palate bone. 

Articulations of the Ethmoid. 

The ethmoid bone articulates with 13 bones which may be 
thus enumerated. 

C Sphenoid. 
"3 Single or Mesial bones (3) ■< Frontal. 



The Ethmoid Bone artic- 
ulates with 13 bones, as 
follows : 



5 pairs of bones (10) 



( Vomer. 

Nasal. 

Superior Maxillary. 

Lachrymal. 

Palate. 

Inferior turbinated. 



Total, 13 

It will thus be perceived that the ethmoid bone articulates 
with all the bones of the upper jaw, with the exception of the two 
malar, and this number is complemented by the addition of the 
sphenoid and the frontal bones of the cranium. 

Muscles. 

The ethmoid bone affords attachment to no muscle. 

Development. 

The ethmoid bone develops by three centres of ossification, 
one of which is situated in each of the lateral masses and one 
within the perpendicular plate of the bone. 

This bone, at the time of birth, presents no attempt at ossifi- 
cation in either the horizontal or the perpendicular plates, but 
ossific granules are present in the lateral masses of the bone. 

The lateral masses become joined to the cribriform plate of 



32 BONES OF THE HEAD. 

the ethmoid at about the end of the first year of life, and the 
lateral masses develop their full expanse of surface, through the 
formation of the ethmoidal cells, at about the sixth year of age. 

THE FRONTAL BONE. 

This bone is situated in the anterior portion of the cranium. 
Its direction is both vertical and horizontal since it consists of two 
portions which form nearly a right angle with each other. The 
vertical part is called the frontal portion of the bone, and the 
horizontal part is termed the orbito-nasal portion. 

The frontal portion of this bone presents for examination, an 
exterior and interior surface, and two strong processes termed the 
external angular and i?itemal angular processes. 

The orbito-nasal portion of the bone, presents for special ex- 
amination two orbital plates, and a notch between them called 
the ethmoidal notch. 

Frontal or Vertical Portion. 

Exterior Surface. 

This surface is convex in shape, and forms the forehead. It 
presents in the median line either an existing suture or a median 
depression which indicates the point of junction of the two lateral 
halves of this portion of the frontal bone. Ossification becomes 
complete in this region, a few years after birth, except in rare 
cases where the suture is not obliterated. 

Below this median suture is a prominent elevation of bone 
termed the nasal eminence. 

On either side of the median suture, are two round elevations 
of bone of quite large size, which are termed the frontal eminences. 

Above the upper margin of the orbital cavity, to which the 
name supra-orbital arch is applied, are perceived two prominent 
ridges of bone, which are produced by the projection forwards of 
that portion of the frontal bone, which covers the frontal sinuses. 
These ridges are called the super-ciliary ridges. 

At about the inner third of the supra-orbital arches, are per- 
ceived two notches for the transmission of the supra-orbital ves- 
sels, and the supra-orbital nerve. These notches are called the 
supra-orbital notches,or, in case a complete foramen exists in place 
of the notch, the opening is called the supra-orbital foramen. 

Interior Surface. 

This surface of the vertical portion of the frontal bone is 
concave and presents the following points of interest. 



ETHMOID BONE. 



33 



In the median line, near the point of junction of the vertical 
and the horizontal portions of the frontal bone, is perceived a 
small foramen called the foramen ccecum. This foramen is usually 
completed by the articulation of the ethmoid bone with the fron- 
tal, but may occasionally exist independently of that bone. It 
transmits a small vein to the longitudinal sinus, and a prolonga- 
tion of the falx cerebri. 

Above this foramen lies a prominent ridge of bone, called the 
frontal crest, which is continued upwards into a vertical groove for 
the attachment of the falx cerebri, and which corresponds to the 
situation of the superior longitudinal sinus of the dura mater. 

On the lateral portions of this surface of the frontal bone are 
perceived impressions which correspond to the convolutions of 
the brain, and which are called the cerebral impressions, and, run- 
ning over the surface of the bone are seen numerous small grooves 
in which are lodged the branches of the anterior and the middle 
meningeal arteries. 

Angular Processes. 

The angular processes of the frontal bone are four in number, 
two of which are situated at the extreme ends of the bone, and 
are termed the external angular processes, while the remaining 
two are located at the centre of the face near to the inner angle 
of the orbital cavity, and are called the inter7ial angular processes 
of the frontal bone. 

External Angular Processes. 

These processes are thick and strong, and afford articulation 
for the two malar bones. They also enter into the formation of 
the anterior part of the temporal ridge. 

Internal A ngular Processes. 

These projections of the frontal bone are thin and afford a 
point of articulation for the lachrymal bones. They furthermore 
bound the so called nasal notch which affords articulation for the 
nasal bones, and the nasal process of the superior maxillary bone. 
They also, by their point of junction, form a sharp long projection 
to which the name nasal spine is applied. 

Orbito-nasal or Horizontal Portion. 

This portion of the frontal bone comprises two orbital plates 
of bone, separated by a notch into which the ethmoid bone is re- 
ceived, and which for that reason is called the ethmoid notch. 



24 BONES OF THE HEAD. 

Orbital Plates. 

These plates present for examination, an upper and an under 
surface. 

The under surface is concave in shape, and forms the upper 
wall of the cavity of the orbit. It contains at its external por- 
tion a depression of quite large size called the lachrymal fossa, 
since it lodges the lachrymal gland, and at its internal portion a 
smaller depression called the fovea trocJilearis into which the 
pulley for the superior oblique muscle of the eye is inserted. 

The upper surface is convex in shape, and helps to form the 
floor of the anterior fossa of the cavity of the cranium. It pre- 
sents for examination only some veil marked cerebral impressions 

Ethmoidal Notch. 

This notch is filled up by the cribriform plate of the ethmoid 
bone. The under surface of the margins of this notch present the 
following points of anatomical interest and importance. 

(i.) Several half cells, which complete and close the corres 
ponding half cells of the ethmoid bone. 

(2.) Two grooves, which also help to complete the anterior and 
posterior ethmoidal canals for the transmission of the 
nasal nerve and the anterior and posterior ethmoidal 
vessels. 

(3.) The nasal spine which here articulates with the perpen- 
dicular plate of the ethmoid, and with the nasal bones, 
and which helps to form a part of the nose. 

(4.) The openings of the frontal sinuses, which are situated 
upon either side of the nasal spine. 

Articulations of the Frontal Bone. 

The frontal bone articulates with 12 bones which may be thus 
classified : 



The Frontal Bone 
articulates with 12 
bones, viz. : 



Two single or mesial , v ( Sphenoid, 
bones. *■ ' \ Ethmoid. 



Parietal. 



1° 



ne Cranial 
bone. 



Five pairs of bones (iok c '. .,, -,-, ^ . . 

* I Superior maxillary. I Four Facial 

T .nrhnmial I hnnpc 



Total, 12 



Lachrymal. bones. 

Malar. J 



Of these 12 bones with which the frontal bone articulates, it 
will thus be perceived that only two are single or mesial bones, 



TEMPORAL BONE. 



35 



and that the remainder consist of five pairs, of which one pair 
belongs to the cranium, and four pairs belong to the face. 

Muscles attached to the Frontal Bone. 

The frontal bone affords attachment to three pairs of muscles. 
These three pairs of muscles are all situated upon the exterior 
surface of the cranium, and are as follows: 

Muscles attached to the Frontal Bone 



( Orbicularis Palpebrarum. 



-\ CORRUGATOR SUPERCILII. 

(3 P airs -> , ( Temporal. 

Development of the Frontal Bone. 

The frontal bone is developed from two centres of ossification, 
one for each lateral half of the bone. At birth the bone consists 
of two pieces which afterwards become united by means of a 
suture running from the sagittal suture to the root of the nose. 

This suture in rare cases remains open throughout life. It is 
called the froittal suture. 

THE TEMPORAL BONE. 

The temporal bones are situated upon either side of the base 
of the cranium. They are called "temporal" {tempus, time), be- 
cause grey hairs first appear in the region of these bones. 

These bones are very irregular in shape and consist of an ap- 
parent union of three distinct portions, which have been named 
respectively the squamous, the mastoid and the petrous portions 
of the bone from certain characteristics which are prominent in 
each. These portions will be described separately, and the 
points of anatomical interest pertaining to each will thus be more 
clearly set forth than if the bone be described as a whole. 

A. Squamous Portion. 

This portion of the temporal bone is so-called from its resem- 
blance to a scale. It is a thin semi-circular plate of bone which 
lies upon the side of the skull, higher up than either of the other 
portions of the temporal bone. It presents for examination two 
surfaces and a circumferential border. 

Outer Surface. 

This surface of the squamous portion is convex in shape and 
enters into the formation of the temporal fossa. It presents for 
examination, 

(i.) The temporal ridge, which forms, however, only a small 
portion of the whole of the entire bony ridge known 
by this name. This ridge is situated at the posterior 
portion of the squamous portion of the bone. 



36 BONES OF THE HEAD. 

(2.) The zygomatic process. This process first projects out- 
wards and subsequently curves forwards. It is broad 
and flattened in form and presents two borders (an 
upper and Tower), two surfaces (outer and inner), an 
apex and a base. 

The upper border is thin and affords attachment to 
the temporal fascia. The lower border is thick and 
shorter than the upper, and affords attachment to the 
masseter muscle. 

The outer surface is convex in shape while the inner 
surface is concave. To the latter surface the masseter 
muscle is attached. 

The apex is serrated and articulates with the malar 
bone. 

The base is formed by three roots called the anterior, 
middle and- posterior root of the zygoma. The an- 
terior root is broad and directed transversely across 
the skull at its base. It forms a bony eminence'called 
the eminentia articularis, which lies in front of the 
articulation of the lower jaw. 

The middle root of the zygoma forms the posterior 
boundary of the glenoid fossa, while the posterior root 
of this process forms the point of origin of the tempo- 
ral ridge. 
(3.) The glenoid fossa. This is a depression of quite large 
size which is comprised between the anterior and the 
middle roots of the zygomatic process. It is divided 
into two parts, an anterior and a posterior, by a fissure 
called the Glaserian fissure, which affords a passage, 
(1) for the laxator tympani muscle, (2) for the tym- 
panic artery, and (3) for the processus gracilis of the 
malleus. A canal, called the canal of Huguier, is 
present in this portion of the bone, for the transmis- 
sion of the chorda tympani nerve. 

The anterior part of the glenoid fossa is articular, 
and is covered with cartilage which is also prolonged 
over the eminentia articularis. It receives the articular 
head of the lower jaw. 

The posterior part of the glenoid fossa is bounded 
behind by the vaginal process, and the auditory pro- 
cess (both of which belong to the petrous portion of 
the bone), and by the middle root of the zygomatic 
process. It lodges the parotid gland and is not for 
the purpose of articulation. 



TEMPORAL BONE. 37 

Inner Surface. 

The inner surface of the squamous portion of the temporal 
bone is concave in its shape and presents marked cerebral im- 
pressions and grooves channelled in its substance for the protec- 
tion of the middle meningeal artery and its branches. 

Circumference. 

The circumference of the squamous portion of the temporal 
bone is very thin above and posteriorly, at which portions it is 
bevelled internally for articulation with the parietal bone. In 
front, the margin is thick and is slightly bevelled upon its 
external surface. 

It articulates, at this latter point, with the great wing of the 
sphenoid bone. 

B. Mastoid Portion. 

This portion of the temporal bone is so called from its resem- 
blance to a nipple. 

It is situated at the posterior part of the bone. Its outer sur- 
face is rough and perforated by numerous small foramina, one of 
which is of large size and is termed the mastoid foramen. It 
transmits a vein to the lateral sinus. 

The tip of this portion of the temporal bone is called the 
mastoid process. It affords attachment to three muscles ; viz., the 
sterno-mastoid, the splenius capitis and the trachelo-mastoid. 

Upon the inner side of this process is perceived a deep groove 
called the digastric groove, which affords attachment to the pos- 
terior belly of the digastric muscle. 

Still further inwards a second groove, parallel to the digastric, 
is perceived, and to this the name occipital groove is given, since 
the occipital artery is lodged within it. 

The inner surface of the mastoid portion of the temporal bone 
forms a part of the posterior fossa of the base of the skull, and it 
is deeply grooved for the lateral sinus. 

The superior border of the mastoid portion is thick and serrated 
as is also the posterior border. The former articulates with the 
inferior angle of the parietal bone and the latter with the lower 
border of the occipital bone. 

C. Petrous Portion. 

The petrous portion of the temporal bone is so called from its 
extreme density (7rer/)of,rock). It is pyramidal in form and is di- 
rected forwards and inwards, being wedged in between the sphen- 



38 BOXES OF THE HEAD. 

oid bone and the basilar process of the occipital bone. It con- 
tains all the bony cavities of the ear within its interior and po- 
sesses therefore great anatomical importance. 

It presents for examination three surfaces, three borders, a 
base and an apex. 

Base of Petrous Portion. 

This is the only exposed part of the petrous portion, and is 
situated at the side of the cranium. It presents (i) an opening 
in it called the meatus auditorius extemus, which corresponds to 
the opening of the external cartilage of the ear, and (2) a bony 
ring which surrounds this opening called the auditory process, to 
which the external cartilage of the ear is attached. 

Apex of Petrous Portion. 

This part of the petrous portion of the temporal bone lies at 
the base of the skull, and is the innermost part of the entire bone. 
It allows of the passage of the internal carotid canal and forms 
the posterior and outer boundaries of the foramen lacerum 
medium or foramen basis cranii. 

The petrous portion of the temporal bone is properly there- 
fore a truncated pyramid, its apex not finishing in a perfect point, 
and it is also, as regards its direction, a pyramid laid upon its side 
rather than one standing upon its base, since its apex points in- 
wards rather than upwards. 

Anterior Surface. 

This surface of the petrous portion of the temporal bone forms 
the posterior boundary of the middle fossa of the base of the 
skull and presents the following points of anatomical interest. 

(1 ) The internal opening of the carotid canal, which transmits 
the carotid artery and the carotid plexus of the sym- 
pathetic system of nerves. 

(2.) The depression for the Gasserian ganglion of the 5 th pair 
of cranial nerves. 

(3.) The hiaius Fallopii. 

This foramen transmits the large petrosal nerve, and 
the petrosal branch of the middle meningeal artery. 

(4.) The foramen for the small petrosal nerve, and occasionally 
a separate foramen for the petrosal branch of the 
glosso-pharyngeal nerve. 

(5.) An eminence produced by the superior semi-circular canal 
of the internal ear. 



TEMPORAL BONE. *g 

(6.) A depression which lies above the location of the tym- 
panum or the cavity of the middle ear. 

Posterior Surface. 

This surface of the petrous portion of the temporal bone 
forms the anterior boundary of the posterior fossa at the base of 
the skull. It presents two openings, as follows : 
(i.) The meatus auditor ius internus. 

The internal canal leading to the cavity of the tympanum 
transmits the facial and auditory nerves and the audi 
tory artery. It also transmits a prolongation of the 
dura mater of the brain. 
(2) The opening of the aquceductus vestibuli. 

This opening transmits a small artery and vein to the vesti- 
bule, and also a process of dura mater. 

Inferior or Basilar Surface. 

The petrous portion of the temporal bone forms a portion of 
the base of the skull. This surface presents the following points 
for special consideration. 

(1.) A diagonal line running from before backwards and out- 
wards. 

(2) The opening of the carotid canal, through which passes the 

internal carotid artery and the carotid plexus of nerves. 

(3) The aquceductus cochlece, which transmits a vein to the 

cochlea. 

(4.) The jugular fossa, which lodges the sinus of the internal 
jugular vein, and which assists in forming the jugular 
foramen or the foramen lacerum posterius. 

(5.) An opening for jfacobsons nerve, which is situated in front 
of the jugular fossa upon a bony ridge between it and 
the carotid canal. 

(6.) An opening for Arnold's nerve, which is situated upon the 
outer wall of the jugular fossa. 

(?.] The jugular surface, which articulates with the jugular 
process of the occipital bone. 

(8.) The vaginal process which embraces the root of the styloid 
process of the temporal bone. 

(9.) The styloid process, which affords attachment to the fol- 
lowing structures from above downwards. 
The stylo-pharyngeus muscle. 
The stylo-hyoid muscle. 



. BONES OF THE HEAD. 

The styloglossus muscle. 
The stylo-hyoid ligament. 
The stylo-maxillary ligament, 
(io.) The stylo-mastoid foramen. 

This foramen transmits the facial nerve and the stylo- 
mastoid artery. 
(n.) A rough surface which affords attachment to the levator 

palati and the tensor tympani muscles. 
(12.) The auricular fissure for the exit of the auricular branch 

of the pneumogastric nerve. 
(13.) The opening of the Aquceductus Cochlece. 

This foramen is situated in front of and to the inner 
side of the jugular fossa, near to the posterior border 
of the petrous portion of the temporal bone. 

Borders of the Petrous Portion. 

The superior border is situated within the cavity of the skull 
and forms the line of separation between the anterior and the 
middle fossce at the base of the skull. 

It is grooved for the superior petrosal sinus and affords at- 
tachment, throughout its entire length, to the tentorium cerebelli. 

The posterior border is grooved for the inferior petrosal sinus 
in front, and, behind, it assists in forming the jugular foramen. 

The anterior border articulates, at its inner part, with the 
spinous process of the sphenoid bone, while, at its outer part, it 
is joined to the squamous portion of the temporal bone. 

At the point of junction of the squamous and the petrous por- 
tions of the temporal, at the retiring angle between them, is 
perceived the canal for the tensor tympani muscle, and the osseous 
portion of the Eustachian tube. 

Upon the outer side of the opening for the Eustachian tube is 
also perceived a small opening, called the canal of Huguier, which 
transmits the chorda tympani nerve. 

Muscles attached to the Temporal Bone. 

The 14 muscles attached to the temporal bone may be clas- 
sified as follows : 



TEMPORAL BONE. 



41 



The Temporal bone gives 
attachment to 14 mus- 
cles, viz, : 



r To squamous portion, 



To mastoid portion, 



To petrous portion, 



To styloid process. 



j Temporal. 
( Masseter. 
TOccipito Frontalis. 
Stekno Cleido Mastoid. 
fi J Splenius Capitis. 



IS 



Trachelo Mastoid. 
Digastric. 

etrahens Aurem. 
Levator Palati. 
Tensor Tympani. 
Stapedius. 
Stylo-Glossus. 
Stylo-Hyoid. 
Stylo-Pharyngeus. 



Total, 14 



Articulations of the Temporal Bone. 

The temporal bone articulates with five bones as follows 



The Temporal Bone ar- 
ticulates with 5 bones. 



Mesial bones, 
Lateral bones, 



! Occipital. 
Sphenoid. 
Inferior Maxillary. 
, N j Parietal. 
W i Malar. 



Total, 5 



Both of the temporal bones, however, articulate with only- 
seven bones ; viz., the three mesial bones, (occipital, sphenoid and 
inferior maxilla) and two pairs of bones (parietal and malar). 



Development of the Temporal Bone. 

The temporal bone is developed by four centres, exclusive of 
those of the internal ear and its ossicula. These four primary 
centres of ossification are arranged as follows : 



The four centres of de- 
velopment of the Tem- 
poral Bone are as fol- 
lows : 



' One for the 
One for the 
One for the 
One for the 



( Squamous portion 
X and the 

( Zygomatic portion. 
\ Auditory process. 
Petrous portion 

and the 
Mastoid portion. 
\ Styloid process. 



At birth this bone consists of three pieces, as indicated above, 
(excluding the styloid process). During the first year these three 
portions become united, the auditory process joining the petrous 
portion of the bone soon after birth. 

The styloid process does not become united, however, until 
the 2nd or 3rd year of age. 



42 



BONES OF THE HEAD. 



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PARIETAL BONE. 

43 

THE PARIETAL BONE. 

This bone forms the side of the skull and is so named from 
{paries — a wall). It is quadrilateral in form and presents for ex- 
amination two surfaces, four borders, and four angles. 

Surfaces. 

The exterior or outer surface is convex and presents three 
points deserving of special mention. 

(i.) The parietal foramen, which is situated at the upper and 

posterior portion of the bone and which transmits a 

vein to the superior longitudinal sinus. 
(2.) A prominent portion of bone termed the parietal eminence. 
(3.) The temporal ridge, which indicates the upper boundary 

of the temporal, fossa of the skull. 
The interior surface of the bone is concave and presents four 
points of special interest, as follows : 

(1.) Cerebral eminences and depressions, which correspond to 

the cerebral convolutions. 
(2.) Furrows in the bone, in which are lodged the ramifications 

of the middle meningeal artery. 
(3.) A half groove near the superior border of the bone, for the 

superior longitudinal sinus of the skull, and for the 

attachment of the falx cerebri. 
(4.) Depressions for the Pacchionian bodies, which are small, 

whitish bodies situated between the dura mater and 

the skull. 

Borders. 

The superior border of the bone forms, by its junction with the 
parietal bone of the opposite side, the sagittal suture. 

The inferior border is bevelled on its outer surface, and is over- 
lapped, in front, by the greater wing of the sphenoid 
bone and by the squamous portion of the temporal 
bone, while, beJiind, it articulates with the mastoid 
portion of the temporal bone. 

The anterior border of the bone is serrated and forms the 
coronal suture by its articulation with the frontal 
bone. 

The posterior border of the bone articulates with the occipital 
bone and thus forms the lambdoidal suture. 

Angles. 

The anterior superior and the posterior superior angles of the 



44 BONES OF THE HEAD. 

parietal bone correspond to the anterior and the posterior fon- 
tanelles. 

The anterior inferior angle is received between the frontal 
bone and great wing of the sphenoid bone, one inch above and 
behind the superior external angle of the orbit. Internally, it is 
often grooved for the anterior branch of the middle meningeal 
artery. 

The posterior inferior angle articulates with the mastoid por- 
tion of the temporal bone and presents, internally, a small portion 
of the groove for the lateral sinus. 

Muscles. 

The parietal bone affords attachment to only one muscle ; viz., 
the temporal muscle. 

Articulations of the Parietal Bone. 

This bone articulates with five bones, which may be thus enu- 
merated : 

( Occipital. 

f Mesial bones 3 ■< Sphenoid. 

The Parietal Bone ar- | (Frontal, 

ticulates with 5 bones, as-( 

f0ll0WS : I Lateral bones 2 \ ^T\ ■ , 

I I Opposite Parietal. 



Both parietal bones articulate also with only five bones as 
follows. The three mesial bones above mentioned and the two 
temporal. Since the two parietal bones meet in the median line 
the parietal articulation common to each one separately is want- 
ing when both are considered together. 

Development. 

The parietal bone is developed from only one centre of ossifi- 
cation, which corresponds with the parietal eminence. 



THE VOMER. 



45 



BONES OF THE FACE. 
The face is composed of 14 bones, which may be divided as 
follows : 

r Mesial bone. . . , . .(1) \ Vomer. 
f Nasal. 

j Sup. Maxillary. 
6pairsofbo„es..( I2 )-! Lachrymal. ' 



f Comprised in upper 
jaw, (13 bones,) 



Bones of the 
Face. (14) 



Palate. 

Inferior turbinated. 



Total, 13 

Forming lower jaw, ( j^. maxin 
(1 mesial bone.) ( J 

THE VOMER. 

This bone forms the posterior and inferior part of the nasal 
septum. It is frequently deflected from the median line towards 
one side. It bears a fancied resemblance to the shape of a plough- 
share and presents for examination four borders and two surfaces. 

It articulates, by a deep groove between two projecting alee 
upon its superior border, with the rpstrum of the sphenoid bone. 
These alse are overlapped inferiorly by the vaginal processes of 
the same bone. 

Its inferior border articulates with a ridge, formed by the 
palate plates of the superior maxillary and the palate bones. 

Its anterior border is grooved above for articulation with the 
perpendicular plate of the ethmoid bone, and below it is joined to 
the cartilage of the septum between the nares. 

Its posterior border is free. It separates the apertures of the 
posterior nares. 

Its lateral surfaces present small grooves for the lodgment 
of small vessels and nerve filaments, and also a larger groove in 
which is lodged the naso-palatine nerve. 

Muscles. 

The vomer affords attachment to no muscle. 
Articulations. 

The vomer articulates with six bones which may be thus clas- 
sified : 

Of the Cranium (Mesial) .... (2) \ §S^ 



^ Ethmoid. 

r\c 4-t, xr c~ • \ r \ \ Superior maxillary. 

Of the Face (2 pairs) (4) -j pj^ 

Total, ~6~ 

These six bones may thus be stated- to consist of two mesial 
bones and two pairs of bones, the former being situated in the 
cranium and the latter in the face. 



46 bones of the face. 

Development. 

Ossification of the vomer commences, by a single centre, in a 
cartilage contained between the two laminae, of which the bone is 
at first composed. This centre appears at about the same time 
as those of the vertebrae. 

THE NASAL BONES. 

These bones form the bridge of the nose. They are narrow 
and thick at their upper portion, and wide and thin at their lower 
extremity. They present for examination two surfaces and four 
borders. 

The outer surface of the nasal bone is convex in shape from 
side to side, and concave from above downwards, especially at its 
upper portion where it bends to give shape to the nose. It pre- 
sents several small grooves for arteries and a small foramen which 
transmits a vein. 

The inner surface of the bone is inversely curved from the 
outer surface and presents a groove for the external branch of the 
nasal nerve. 

The superior border is thick and narrow and articulates with 
the frontal bone. 

The inferior border is broad and thin and is joined to the 
lateral cartilage of the nose. It presents a notch which transmits 
the nasal nerve. 

The external border of the nasal bone articulates with the 
nasal process of the superior maxillary bone. 

The internal border of the nasal bone articulates with its fel- 
low in the mesial line of the face. It is prolonged backwards 
and upwards into a crest which articulates with the nasal spine 
of the frontal bone and with the perpendicular plate of the eth- 
moid bone. 

Muscles attached. 

No muscles are directly attached to this bone. 

Articulation. 

f 2 bones of Cranium.. . \ !™ nta !\ 

/ Ethmoid. 

The Nasal Bone articulates with four J r ax 1 

bones, as follows: 1 . f ., ~ ) £ asai : .. 

| 2 bones of the Face.. . < Superior maxil- 



,.j 



Development. 

This bone is developed by one centre of ossification. 



SUPERIOR MAXILLARY BONE. 47 

THE SUPERIOR MAXILLARY BONE. 
This bone assists in the formation of the following parts : 

C The roof of the mouth. 

3 cavities \ The floor and outer wall of the nose. 

( The floor of the orbit. 
. I The zygomatic fossa. 

2 fossae } The temporal fossa. 

- j The spheno-maxillary fissure. SaJUt^ 

2 nssures "j The pterygo-maxillary fissure. I 

The bone, as a whole, may be described as presenting a body 
and four processes, viz., the malar, nasal, alveolar and palate pro- 
cesses, each of which will be separately described. 

A. The Body. 

This portion of the bone is hollow. Its cavity is termed the 
antrum of Highmore. The body of the superior maxillary bone 
may be divided into three surfaces and its central cavity. 

( 1 .) Outer or facial surface of body. 

This portion of the body of the bone is convex in its form. 
It presents, as the bone is examined from within outwards, several 
points which have been specially named. 

The incisive fossa, or myrtiform fossa, is a depression in the 
outer surface of the body of the bone, near the median line, for 
the attachment of the depressor alae nasi muscle. 

The canine fossa is a large, deep depression situated immed- 
iately below the infra-orbital foramen, and it affords attachment 
for the levator anguli oris and the compressor naris muscles. The 
foramen immediately above it transmits the infra-orbital vessels 
and nerve. 

The maxillary tuberosity is situated behind a vertical bony 
ridge upon the outer surface of the body of the bone. It affords 
articulation for the tuberosity of the palate bone. 

(2.) Inner surface of body. 

This portion of the bone is divided into two unequal parts 
by its palate process. The portion below this process forms 
the anterior part of the roof of the mouth, while the portion 
lying above the palate process forms the largest part of the outer 
wall of the nasal cavity, and presents the following points of spec- 
ial interest. 

The inferior turbinated crest, a ridge of bone separating two 
wide and deep grooves, which run in an antero-postcrior direction 
and which correspond to the middle and inferior meatuses of 
each of the nasal fossae. 

The superior turbinated crest, a ridge of bone surmounting 



48 BONES OF THE FACE. 

the groove which corresponds to the situation of the superior 
meatus of the nose. 

Upon the inner surface of the body, is furthermore seen a 
groove, which enters into the formation of the nasal duct, by 
its articulation with the lachrymal and the inferior turbinated 
bones. 

The aperture of the Antrum of Highmore is also perceived 
upon this surface of the body of the bone. It is a very large 
opening in the disarticulated bone, but during life or in the com- 
plete skull it is of small size, being diminished by the articula- 
tions of the ethmoid, lachrymal, inferior turbinated and palate 
bones. 

Two other points remain upon this surface which deserve 
notice. The first is a vertical groove which helps to form the 
posterior palatine canals, and the second is a rough surface which 
is traversed by the vertical groove previously mentioned, and 
which affords attachment for the articulating surface of the palate 
bone. 

(3.) Upper or orbital surface of body. 

This portion of the superior maxillary bone forms the greater 
part of the floor of the orbit. 

Upon its inner border, it is bounded by a thin edge of bone 
which articulates with the lachrymal bone, the os planum of the 
ethmoid bone and the orbital process of the palate bone. 

Upon its outer border, it is bounded by a rounded margin 
which forms a part of the spheno-maxillary fissure, while, in front, 
it forms the lower part of the circumference of the orbit. 

Upon this surface of the bone is seen, at its posterior portion, 
the infra-orbital groove, which becomes the infra-orbital canal at 
the anterior portion, near to the circumference of the orbit. This 
canal transmits the infra-orbital nerve. A depression for the in- 
inferior oblique muscle of the eye is also perceived. 

(4.) The Antrum of Highmore. 

This cavity in the body of the superior maxillary bone is also 
called the maxillary sinus. 

Its walls correspond to the three surfaces of the body of the 
bone. They are very thin, and contain the infra-orbital, the 
anterior dental and the posterior dental canals. 

Its aperture communicates with the middle meatus of the 
nasal fossa and is of small size in the living subject. 

The 1st and 2nd molar teeth project through its floor, and, in 
case of abscess of the antrum, these teeth are often drawn to es- 
tablish drainage. 



SUPERIOR MAXILLARY BONE. 49 

(B.) The Malar Process. 

This portion of the superior maxillary bone is triangular in 
form and presents for examination three surfaces. 

Its anterior surface is concave in form and forms a part of the 
canine fossa. 

Its posterior surf ace is also concave in its form and enters into 
the construction of the zygomatic fossa. 

Its superior surface is roughened for articulation with the 
malar bone. 

(C.) The Nasal Process. 

This process, like the one preceding, is of a triangular form. 
It presents for examination two surfaces and two borders. 

The outer surface is concave and affords attachment for the 
obicularis palpebrarum, and the levator labii superioris alaeque 
nasi, muscles and also for the tendo oculi. 

The inner surface presents for examination the following 
points of interest : 

(i.) A roughened portion, for articulation with the ethmoid 

bone. 
(2.) A superior turbinated crest, which articulates with the 
middle turbinated bone of the ethmoid, which has 
been described in connection with the inner surface of 
the body of the bone. 
(3.) An inferior turbinated crest, which separates the two 
grooves corresponding to the middle and the inferior 
meatuses of the nose. 
The anterior border of the nasal process is thin and is serrated, 
at its upper portion, for articulation with the nasal bone, while, at 
its lower portion,it becomes continuous with the margin of the 
anterior opening of the nasal fossa. 

The posterior border presents a groove which helps to form the 
nasal duct. This groove articulates, at its inner margin, with the 
lachrymal bone, while its outer margin forms a part of the cir- 
cumference of the orbit and terminates in the lachrymal tubercle. 

(D.) The Alveolar Process. 

The alveolar process of the superior maxillary bone forms, upon 
either side, the horse-shoe curve of the line of the teeth. It is 
much thicker at its posterior portion than in front, since the teeth 
are wider behind, and it presents, in the adult, articulations or 
alveoli for eight teeth, and, in the child, for five teeth only. 



50 



BONES OF THE FACE. 



(E.) The Palate Process. 

This portion of the bone presents for examination two sur- 
faces and three borders. 

The upper surface is concave, from side to side, and forms 
a portion of the floor of the nasal fossa. It presents, in its an- 
terior portion, a foramen called the incisor foramen, or the fora- 
men of Stenson. This foramen leads into a canal, called the ante- 
rior palatine canal, as do also two smaller foramina, which can be 
seen only from the under surface of the palate process and which 
are called the foramina of Scarpa. 

The foramina of Stenson transmit the anterior palatine vessels 
and the foramina of Scarpa transmit the naso-palatine nerves. 

The under surface of the palate process of the superior 
maxillary bone is concave and forms the anterior portion of 
the roof of the mouth. It has a rough surface and is channelled 
by a groove (occasionally by a complete canal) for the protection 
of the posterior palatine vessels and the anterior or great palatine 
nerve. At its posterior part, is seen the lower orifice of the pos- 
terior palatine canal. 

The inner border of the palate process is raised into a ridge 
which, with its fellow, forms a groove for the vomer. At its an- 
terior extremity, a projection, called the anterior nasal spine, is 
perceived. 

The anterior border of the palate process forms the lower part 
of the anterior aperture of the nasal fossa. 

The posterior border of the palate process articulates with the 
horizontal plate of the palate bone. 

Muscles attached to the Superior Maxillary Bone. 



The Superior Max- 
illary bone gives i 
attachment to 1 1 
muscles, as follows : 



To nasal process (2) 



To body, ■< 



'Outer surface. . 

Facial surface. . 
Orbital surface. 



To alveolar process (1) 

To malar process (1) 

I To the tuberosity (1) 



Orbicularis palpebrarum. 
Levator labii superioiis 
alaequa nasi, 
f Levator proprius labii su- 
periods. 
(4) < Levator anguli oris. 
Compressor naris. 
(^ Depressor alse nasi. 
(1) ( Orbicularis oris. 
/ ^ •< Inferior oblique of the 
W ( Eye. 

Buccinator. 
Masseter. 
External pterygoid. 



Total, 11 



lachrymal bone. 5 1 

Articulation. 



{ Mesial bones ... (3) X 



Frontal. 
Ethmoid. 
The Superior Maxillary bone j \ Vomer, 

articulates with 9 bones, as fol- < f Nasal, 

lows : I Opposite Sup. Maxillary. 

Unbones.... (6) ^chrymal. 

Palate. 
— [Inferior turbinated. 
Total, (9) 

Development. 

f For nasal and facial portions I centre* 

The Superior Maxillary bone ] " orbital and malar " 1 centre. 

is developed by four centres of < " incisive portion of the bone I centre. 

ossification, as follows : " palate " " 1 centre. 

Total, 4 

THE LACHRYMAL BONES. 

These bones of the face help to form the inner wall of the 
cavity of the orbit. Each bone presents for examination two 
surfaces and four borders, since it is nearly quadrilateral in shape. 

The outer surj ~ace of the bone presents for special examination 
the following points. 

(1.) A marked groove, which forms a part of the nasal duct. 

(2.) A ridge, which affords attachment to the tensor tarsi 
muscle. 

(3.) A smooth surface, which forms the inner wall of the orbit. 

The inner surface forms a portion of the anterior part of the 
middle meatus of the nose, and articulates, at its posterior ex- 
tremity, with the ethmoid bone. It presents a furrow which 
corresponds to the ridge upon the outer surface of the bone. 

The anterior border articulates with the nasal process of the 
superior maxillary bone. 

The superior border articulates with the internal angular pro- 
cess of the frontal bone. 

The posterior border of the bone articulates with the os planum 
of the ethmoid. 

The inferior border articulates with the orbital plate of the 
superior maxillary bone, and, in front, it is prolonged into a 
pointed process, called the hamulus laclirymalis, which articulates 
with the lachrymal process of the inferior turbinated bone, and 
which forms part of the nasal duct. 

Muscles. 

The lachrymal bone affords attachment to only one muscle, 
viz., the tensor tarsi. 



52 bones of the face. 

Articulations. 

The lachrymal bone articulates with four bones as follows : 



Articulations of the Lachrymal ( 2 bones of C ™ ium ' { Ethmoid. 

B ° ne * ( 2 hazes at Face. j Superior maxillary. 

_ ( Interior turbinated. 

Total, 4 

Development. 

The lachrymal bone is developed from one centre of ossi- 
fication. 

THE MALAR BONES. 

These bones of the face enter into the formation of the cavi- 
ties of the orbits, the temporal fossae, and the zygomatic fossae. 

They are situated at the outer sides and upper portion of the 
face, and they present for examination two surfaces, three pro- 
cesses and four borders. 

(i.) The outer surface. 

This portion of the bone is convex in form and affords attach- 
ment to the zygomatic muscles. Upon it, is perceived a small 
foramen which transmits the malar branch of the temporo-malar 
nerve. 

(2.) The i?iner surface. 

This surface articulates with the superior maxillary bone, 
internally, and, externally, it is concave and assists in form- 
ing the temporal and zygomatic fossae. It also presents a fora- 
,men which transmits the temporal branch, of the orbital or tem- 
poro-malar nerve. 

(3.) The orbital process. 

This portion of the malar bone projects backwards, and thus 
forms a portion of the outer wall and of the floor of the orbit and 
also a portion of the temporal fossa. It articulates, from above 
downwards, with the frontal, the sphenoid, and the superior max- 
illary bones. It bounds the spheno-maxillary fissure, anteriorly, 
and presents one or two small temporo-malar foramina. 

(4.) The frontal process. 

This process of the bone is thick and directed vertically up- 
wards. It serves for the purpose of articulation with the external 
angular process of the frontal bone. 

(5 .) The zygomatic process. 

This portion of the malar bone is long and is directed hori- 
zontally backwards. It articulates with the zygomatic process 
of the temporal bone. 



PALATE BONE. 53 

(6 ) The borders, of the malar bone. 

The antero-superior border forms the lower and outer portion 
of the circumference of the orbit. 

The anteroinferior border articulates with the superior max- 
illary bone, upon the cheek. 

The postero-superior border and the postero-inferior borders of 
the malar bone are continuous, respectively, with the superior and 
the inferior margins of the zygomatic process of the malar bone. 

Muscles of the Malar Bone. 

This bone affords attachment to five muscles as follows: 

(1.) The levator labii superioris proprius. 

(2.) The zygomaticus major. 

(3.) The zygomaticus minor. 

(4.) The masseter. 

(5.) The temporal. 
Articulations. 

The malar bone articulates with four bones which may be 
thus enumerated : 

i Frontal. 
Sphenoid 



four bones, viz. : j \ ". 

Of the Face, (1.) -{ Superior maxillary. 

Total, 4 

Development. 

The malar bone develops by a single centre of ossification, 
which appears at about the 8th to 10th week of foetal life. 

THE PALATE BONES. 
This bone presents for examination the following component 
parts : 

A. Horizontal plate. 

B. Vertical plate. 

C. Pterygoid process. 

D. Orbital process. 

E. Sphenoidal process. 

The palate bones assist in forming the following parts: (1.) 
The outer wall and floor of the nasal fossa, (2.) the roof of the 
mouth, (3.) the floor of the orbit, (4.) the pterygoid, and spheno- 
maxillary fossa, (5.) the inner wall of the antrum. 

A. The Horizontal Plate. 

This portion of the bone enters into the construction of the 
roof of the mouth, and the floor of the nose. 



54 BONES OF THE FACE. 

Its superior or nasal surface is smooth and concave in form, 
and forms the posterior portion of the floor of the nose. 

Its inferior or buccal surface is roughened and helps to form 
the roof of the mouth. It presents the following points of 
interest. 

(i.) A transverse ridge, for the attachment of the aponeurosis 
of the tensor palati muscle. 

(2.) A deep groove, which assists in forming the posterior 
palatine canal. 

(3.) The external and posterior small palatine foramina, which 
transmit the external and the posterior palatine nerves. 

Its anterior border is serrated for articulation with the palate 
process of the superior maxillary bone. 

Its posterior border is free and affords attachment for the soft 
palate. 

Its inner border is thick and is surmounted by a ridge of bone, 
which, by articulation with its fellow, forms a groove with which 
the vomer articulates. The posterior extremity of this border, 
when united to its fellow of the opposite side, forms the posterior 
nasal spi?ie to which the azygos uvulae muscle is attached. 

(B.) The Vertical Plate. 

This portion of the bone has two surfaces and three borders 
which demand description. 

The inner surface exhibits, like the palate process and inner 
surface of the body of the superior maxillary bone, a superior and 
middle turbinated crest, and two grooves for the superior and 
middle meatuses of the nose. 

The outer surface presents for examination the following 
points of special anatomical importance. 

(1.) A smooth surface, which forms the inner wall of the 

spheno-maxillary fossa. 
(2.) A vertical groove, which assists in forming the posterior 

palatine canal. 
(3.) A roughened surface, with which the superior maxillary 

bone articulates. 
(4.) A smooth surface, situated in front of the vertical groove, 

which forms part of the inner wall of the antrum. 
(5.) A roughened surface, with which the pterygoid process of 
the sphenoid articulates. This surface is situated be- 
low the one for articulation with the superior maxillary 
bone. 
The anterior border is thin and irregular in shape. It sends 



THE PALA TE BONES. 



55 



off a projection called the maxillary process, which helps to close 
the orifice of the antrum. 

The posterior border of the palate bone articulates with the 
inner plate of the pterygoid process of the sphenoid bone. 

The upper border of the same plate presents an anterior process, 
called the orbital process, and a posterior projection, termed the 
sphenoidal process. These two processes are separated by a deep 
notch which forms, by its articulation with the sphenoid bone, 
the greater part of the spheno-palatine foramen, which transmits 
the spheno-palatine nerves. 

C. The Pterygoid Process. 

This process of the palate bone fits into the notch between 
the two plates of the pterygoid process of the ethmoid bone, and 
it presents for examination a posterior surface, two lateral sur- 
faces, and an inferior surface. 

The posterior surface enters into the formation of the ptery- 
goid fossa. 

The two lateral surf aces are roughened for articulation, with 
the pterygoid plates of the ethmoid bone, and with the superior 
maxillary bone. 

The under surface of this process forms a portion of the roof 
of the mouth, and presents for examination the external and 
posterior small palatine foramina, which transmit the external and 
posterior palatine nerves. 

D. The Orbital Process. 

This process projects upwards and outwards from the anterior 
portion of the upper border of the vertical plate of the palate 
bone. It presents three articular surfaces, and two non-articular 
surfaces. 

The three articular surfaces are named, respectively, the an- 
terior, posterior, and internal. They articulate, in this order, 
with the superior maxillary bone, the sphenoid bone, and the 
ethmoid bone. 

The non-articular surfaces are called the superior or orbital, 
and the external or zygomatic. The former forms a portion of 
the floor of the orbit, and the latter forms a portion of the anterior 
wall of the spheno-maxillary fossa. 

These two non-articular surfaces are separated from each other 
by a rounded border, which forms a portion of the spheno-max- 
illary fissure. 



56 BONES OF THE FACE. 

E. The Sphenoidal Process. 

This projection from the palate bone curves upwards, back- 
wards and inwards. 

It presents for examination three surfaces, viz. : an upper, 
outer, and inner surface. 

The upper surface articulates with the sphenoid bone, and 
assists in forming the pterygo-palatine canal. 

The outer surface articulates with the pterygoid process of 
the sphenoid bone, and forms a small portion of the surface of the 
inner wall of the spheno-maxillary fossa. 

The inner surface is concave in its form and forms a portion 
of the outer wall of the nasal fossae. 

Muscles attached to the Palate Bone. 

rTo posterior nasal spine (i) \ Azygos Uvulae. 

The Palate Bone affords | C Internal pterygoid. 

attachment to five mus--{ To pterygoid process (3) < External pterygoid. 

cles, as follows : ( Superior constrictor. 

I To horizontal portion (1) ~{ Tensor palati. 

Total, 5 

Articulations of Palate Bone. 

r I Sphenoid. 

The Palate Bone articu- J Mesial bones ■ — &> \ ™™ id ' 

lates with six bones, viz. ; J . ' omer - 

I ( Opposite Palate bone. 

Lateral bones (3) J Superior maxillary. 

( Inferior turbinated. 

It will thus be perceived that three of these bones are mesial 
bones, and three are situated in the face upon either side of the 
median line of the body. 

Development of Palate Bone. 

The palate bone develops by a single centre of ossification, 
which is located at the point of junction of the horizontal and the 
vertical plates of that bone. 



THE INFERIOR TURBINATED BONES. 

This is a thin curved plate of bone which extends along the 
outer wall of the nasal fossa. 

It presents for examination two surfaces, an outer and inner, 
and an upper and lower border. 

The outer surface is concave, and forms a part of the inferior 
meatus of the nose. 

The inner surface is convex, and presents also vascular 



THE INFERIOR MAXILLARY BONE. 57 

grooves and canals. It looks outwards and forms a portion of 
the outer wall of the nasal fossa. 

The upper border of the inferior turbinated bone articulates, in 
front, with the inferior turbinated crest of the superior maxillary 
bone. It presents also for examination the following points of 
interest. 

(1.) The lachrymal process, which articulates with the lachry- 
mal and the superior maxillary bone and helps to form 
the nasal duct. 
(2.) The maxillary process, which curves downwards and out- 
wards over the lower edge of the orifice of the antrum 
of Highmore. 
(3.) The ethmoidal process, which ascends to join the unciform 

process of the ethmoid bone. 
The lower border of this bone is free and is about one-half inch 
above the floor of the nose, so that sufficient room exists to pass 
the tube of a stomach-pump, if circumstances should demand it. 

Muscles. 

No muscle is attached to the inferior turbinated bone. 

Articulation. 

The INFERIOR TURBINATED W ( Medal h °™ « < Ethmoid. 

articulates with four bones, viz. : 1 ( Superior maxillary. 

\ Lateral bones (3) < Lachrymal. 

( Palate. 

Development. 

The inferior turbinated bone is developed by one centre of 
ossification, which appears about the middle of foetal life. 

THE INFERIOR MAXILLARY BONE. 

The lower jaw is one of the mesial or single bones of the body. 
It is shaped like a horse-shoe, and consists of a middle horizontal 
portion called the body of the bone, and two lateral vertical por- 
tions called the rami of the bone. These two portions will be ex- 
amined separately. 

Body. 

This portion of the inferior maxillary bone presents for ex- 
amination an exterior and interior surface, and a superior and 
inferior border. 

The exterior or cutaneous surface is convex, from side to side, 
and concave, from above downwards. It presents the following 
points of special interest : 



58 BONES OF THE FACE. 

(i.) The symphysis of the chin, which is a vertical ridge situ- 
ated in the median line. 

(2.) The mental process or the process of the chin, from which 
is given off an oblique line, called the external oblique 
line of the jaw, which becomes continuous with the 
anterior border of the ramus and which affords attach- 
ment to the depressor labii inferioris and the depressor 
anguli oris muscles. 

(3.) The incisive fossa, which is situated above the oblique 
line of the jaw, and which affords attachment to the 
levator menti muscle. 

(4.) The mental foramen, which lies externally to the incisive 
fossa and which transmits the mental vessels and 
nerve. 

(5.) A space above the oblique line, which affords attachment 
to the buccinator muscle, and one, below the oblique 
line, for the attachment of the platysma myoides. 

The interior or buccal surface, of the lower jaw is concave 
from side to side, and convex, from above downwards. It pre- 
sents the following points for special description : 

(1.) A median depression, corresponding to the symphysis an- 
teriorly. 

(2.) The superior and inferior pairs of genial tubercles, which 
are located upon either side of the median depression, 
and which afford attachment to the genio-hyo-glossus 
and the genio hyoid muscles. 

(3.) The mylo-hyoid-ridge, which corresponds to the oblique 
line on the outer surface of the bone. It affords at- 
tachment for the mylo-hyoid muscle. 

(4.) The sublingual fossa for the sublingual gland, which is 
situated on either side of the genial tubercles, near to 
the symphysis. 

(5.) A rough depression, which is situated below the mylo- 
hyoid ridge, for the attachment of the anterior belly 
of the digastric muscle. 

(6.) The submaxillary fossa, for the submaxillary gland, which 
is located at the external portion of the body of the 
bone, below the mylo-hyoid ridge. 

The superior border of the body of the bone, is thickest where 
the back teeth are inserted, and presents in the adult sixteen alve- 
oli, and in the child ten alveoli. 

The inferior border of the bone, is thickest anteriorly, where it 
is slightly everted. 



the inferior maxillar v bone. 59 

Ramus. 

This portion of the lower jaw is quadrilateral in form and pre- 
sents the following points, which deserve special mention: 
(1.) The internal surface. 

This surface of the ramus of the jaw presents, near its middle, 
the aperture of the inferior dental ca?tal, for the passage of the 
inferior dental vessels and nerve, in front of which is also per- 
ceived the spine of the ramus, for the attachment of the inter- 
nal lateral ligament of the jaw. A prominent groove called the 
my lo-hyoid groove also exists upon this surface, in which lie the 
mylo-hyoid vessels and nerve, and behind this is seen a roughened 
surface, for the attachment of the internal pterygoid muscle. 
(2.) The external surface. 

On this surface are seen numerous oblique ridges for the at- 
tachment of the masseter muscle. 
(3,) The upper border. 

This portion of the bone presents three points of interest, 
viz. : the coronoid process, the condyloid process, and the sig- 
moid notch. 

The coronoid process is triangular in form and affords attach, 
ment to the temporal muscle. At its lower and ante- 
rior part is perceived a groove which is continued down- 
wards upon the alveolar process and which affords 
attachment to the buccinator muscle. 
The condyloid process consists of two parts, viz. : the condyle 

and the neck. 
The condyle is oblong in its form and convex from side to side 
and from before backwards. The long axis of the con- 
dyle, if prolonged inwards and slightly backwards, would 
meet its fellow at about the region of the anterior bor- 
der of the foramen magnum in the occipital bone. It 
articulates with the glenoid fossa of the temporal bone. 
The neck of the condyloid process is flattened from before 
backwards and is convex on its posterior surface. In 
front, it is hollowed out into a cavity, the pterygoid 
fossa, for the attachment of the external pterygoid 
muscle, and externally it presents a tubercle, for the 
attachment of the external lateral ligament of the jaw. 
The sigmoid notch is a deep depression of a semilunar shape, 
lying between and separating the two processes. It is 
crossed by the masseteric vessels and nerve. 
(4.) The anterior border. 
This border of the ramus is continuous with the external ob- 



6o 



BONES OF THE FACE. 



lique line upon the outer surface of the body. It is thin above, 
but below, where it is grooved for the buccinator muscle, it is much 
thicker. 

(5.) The lower and posterior border. 

These borders are both thick and rounded, and form by their 
junction the angle of the jaw. This point gives attachment to 
the masseter, and the internal pterygoid muscles, and to the 
stylo-maxillary ligament. 

Muscles. 

The muscles attached to the lower jaw, number fifteen pairs, 
and may be thus classified : 



The Inferior 
Maxillary 
Bone gives 
attachment to^ 
15 pairs of 
muscles, a 5 
follows : 



To Body. (11 



>- 



To external surface (6) < 



Levator menti. 
Obicularis oris. 
Depressor labii inferioris. 
Depressor anguli oris. 
Platysma myoides. 
^ Buccinator. 

f Genio-hyo-glossus. 
I Genio-hyoid. 

I To internal surf ace. (s)\ B^J" '-, 
VJ/ I Mylo-hyoid. 

Superior constrictor of pha- 
rynx. 

To external surf ace. {i)\ Masseter. 
To internal surface .{f)\ Internal pterygoid. 
To coronoid process .{\)\ Temporal. 
To neck of condyle. {\)\ External pterygoid. 

Total, 15 pairs. 



Articulation. 

The lower jaw articulates with one pair of cranial bones, viz. 
the two temporal bones. 



I To Ramus (4) 



Development. 

This bone is developed, before any bone in the body, ex- 
cept the clavicle. It probably has two centres of ossification, 
one for each lateral half of the bone. By some authorities addi- 
tional centres are described as existing in the condyle, the coro- 
noid process, the angle, and in a thin plate of bone on the inner 
side of the alveolar border. 



SA TURKS OF THE SKULL. 



61 



Table of the Articulations and the Muscles of the 
Bones of the Cranium. 





Name of Bone. 


Articulation. 


Muscles attached. 


Occipital 


6 bones. 

12 " 

13 " 
12 " 

5 " 

5 " 


12 pairs. 
12 " 

3 muscles. 
14 " 
1 " 


Sphenoid 


Ethmoid 


Frontal 


Temporal 


Parietal 





SUTURES OF THE SKULL. 

In examining the exterior portion of the cranium, we are led 
to observe that certain well-marked lines exist, which indicate 
either actual or previously existing points of separation between 
the various bones composing it. To these lines the name of 
sutures is applied. 

The number of sutures existing between the bones of the 
cranium may be deduced by computing the number of cranial 
bones with which each cranial bone articulates, and thence com- 
puting the number of sutures that may possibly be formed. We 
thus find that thirty-four articulations exist within the cranium, 
as follows : 



Occipital 


articulates with 


5 


:ranial bones. 


Sphenoid 


" 


" 


7 


" * 


Ethmoid 


" 


u 


2 


<« ♦« 


Frontal 


" 


" 


4 


<< 4 


Temporal 


<< 


" 


6 


<< <( 


Parietal 


<i 


" 


10 


C( M 



Total 34 articulations. 

Now as it requires two bones to form a suture, by dividing 
the total number of articulations by 2 we get 17 as the number 
that must necessarily exist. These 17 sutures may be arranged 
in two ways as follows : 

Sutures at the vertex 5 
" sides 4 
" base 8 

Total 17 



62 THE SKULL IN GENERAL. 

f Inter-parietal or Sagittal. 
In the mesial | Occipito-sphenoidal or Basilar 
line of the ^ Spheno-ethmoidal. 
Skull (5) j Spheno-frontal. 

^ Ethmo-frontal. 
At the Vertex, x j Fronlo-parietal of Coronal (one on either side) 
of the Skull^ I Occipito-parietal or Lambdoidal (one on either side) 

Sutures of the . ,- Spheno-parietal 

Cranium. ' . , ., (one on either side) 

flu I! n(4) \ Tempero-parietal j Squamo-parietal. 

of the Skull™ j * (one Qn dther side) \ Masto-parietal. 

f Occipitotemporal ( Occipito-petrosal. 

. , , (one on either side) ] Occipito-mastoidal. 

r\.t tne Dase/ \ 1 

of the Skull -I Spheno . ternporal r Spheno-petrosal. 

[_ (one on either side) ( Spheno-squamosal. 

The masto-parietal suture used formerly to be called the " ad- 
ditamentum sutura squamosa," and the occipito-mastoid suture 
was termed the " additamentum sutura lambdoidalis." These two 
sutures, if taken together, constitute the mastoid suture. 

The inter-parietal suture in children, and occasionally in adults, 
is prolonged through the frontal bone to the nose under the name 
of the frontal suture. 

It thus appears that between the bones of the cranium the 17 
sutures, as shown above, exist, but, by assigning special names to 
portions in which the constituent parts of the temporal bone enter, 
this number will be increased by six, making in all 23, and if the 
frontal suture be included the total number will be 24. 

THE DIFFERENCES IN THE FORM OF THE SKULL. 

The skull presents variations in form which are dependent 
either upon age, sex, or national characteristics. 

In the earlier stages of fcetal life, the posterior part of the 
cranium is greatly in excess of the anterior portion ; but as de- 
velopment proceeds, the parietal region increases rapidly in its 
size, and subsequently the frontal region is greatly augmented. 

During the first years of childhood, the upper part of the 
skull develops more rapidly than its base. The proportion of the 
face to the entire bulk of the skull gradually increases from the 
date of birth, at which time it forms only one-eighth of the entire 
bulk, till adult life is attained, when the proportion reaches nearly 
one-half. 

The female skull is smoother, lighter, and generally of smaller 
size than that of the male, and other points of distinction exist. 

The face is smaller in proportion to the cranium, the muscular 
prominences are less marked, the frontal sinuses are smaller, the 
jaws are narrower, and the frontal and occipital regions are less 



ANTERIOR REGION OF THE SKULL. 63 

capacious in proportion to the parietal. The skulls of different 
races of men frequently present characteristic types as was first 
distinctly pointed out by Camper. The size of the skull in the 
various nations often exhibit marked differences ; thus in the 
Hindoo and the ancient Peruvian, the smallest skulls are discov- 
ered, while among the Scandinavian races and the Caffre, the most 
massive skulls are found. Among rude tribes various characters 
are often found, which serve to distinguish their skulls from those 
of civilized nations; among these characters may be mentioned a 
prominence of the temporal ridges, a greater width of the zygo- 
matic arches and of the anterior nares, a greater length and 
strength of the jaws and a projection forwards of the incisor teeth, 
so that both sets of teeth meet at a sharp angle instead of per- 
pendicularly as in cultivated nations. 

Irregularities of form, if such exist in the skull, are due either 
to mechanical causes or to a premature obliteration of certain of 
the sutures of the skull, known by the name of synostosis. 

ANTERIOR REGION OF THE SKULL. 

The face is bounded, above, by the nasal eminences and the 
upper margins of the orbit, and, below, by the prominence of the 
chin. On either side of the face, the malar bones and the ramus 
of the jaw establish its outline. 

The cavity of the nose is marked, anteriorly, by a heart-shaped 
opening in the face which is termed the opening of the anterior 
nares. 

Across the line of junction of the frontal base or the forehead 
and the bones of the upper jaw, can be traced a line of separation 
called the transverse suture of the face. It begins at the external 
angular process of the frontal bone and extends to the median 
line, at the root of the nose. It separates the frontal bone, suc- 
cessively, from the malar, the sphenoid, the ethmoid, the lachry- 
mal, the superior maxillary and the nasal bones. 

In the mesial line of the face, is also seen a suture which sep- 
arates the two nasal bones, above, and the two superior maxillary 
bones, below, while, even in the lower jaw, the symphysis of the 
chin indicates the previous existence of a fcetal suture. 

The various points of interest pertaining to the osteologv of 
the face have been considered in the special descriptions of the 
individual bones which compose it. 

The face as a whole is of oval form. It presents an irregular 
surface which is excavated by four large cavities, viz., the orbits 
and nasal fossae, in which are lodged two principal organs of spec- 
ial sense. 



64 the skull ln general. 

The Bony Orbit. 
The orbital cavities are two in number, one on either side of 
the nasal fossae. Each cavity is of the form of a quadrilateral 
pyramid whose axis looks outwards and forwards. Each is com- 
posed of seven bones, as follows : 

( Frontal. 
Mesial bones (3) •< Ethmoid. 

( Sphenoid. 

f Superior Maxillary. 
Pairs of bones (4) X m^?™* 1 ' 

I Palate. 

The three mesial bones, mentioned above, enter into the forma- 
tion of both orbits, while one of each pair compose the remainder 
of each orbit. It will thus be perceived that only eleven bones are 
present in the two orbits. 

Each orbit communicates with one cavity, four fossae and one 
canal. The following table will illustrate the means of communi- 
cation with each of these, as well as the names of the parts to 
which the orbit has access. 



The Orbit communi- 
cates with the fol- 
lowing parts of the 
skull 



{Through optic fora- ( 
men and sphenoid- •< Cranium, 
al fissure. ( 

J Through the spheno- f T ^ 'j 
Four fossa . . \ maxillary fissure and -I z ^ ati ^ 

1 nasal duct. ( Sphenomaxillary. 

One Canal \ Nasal duct. 



The orbit presents for examination the following parts : A 
roof, a floor, an inner wall, an outer wall, four angles, a circum- 
ference or base, and an apex. 

The roof oi the orbit is formed by the fol- ( Orbital plate of Frontal, 
lowing two bones : ( Lesser wing of Sphenoid. 

„. „ e ', . . . . , . L , - , (Orbital surface of the Superior Maxilla. 

The floor of the orbit is formed by the fol- j Qrbital egs of the M £ lar< 

lowing three bones : ] 0rbital ^ rocess of the p alate _ 

„, 7, /• .i ^^.^ r j v. f Nasal process of the Superior Maxilla. 

The inner wall of the orbit is formed by ] L ac h r ym a i 

the following four bones in their order, <j 0s planum of the Ethmoid. 

from before backwards : [ Body of the Sphenoid. 

The outer wall of the orbit is formed by the ( Orbital process of Malar. 

following bones in their order, from be- -{Orbital surface of the great wing of the 
fore backwards : ( Sphenoid. 

The points of interest pertaining to each of these special 
localities are as follows : 
ROOF of the orbit, 

(1.) The lachrymal fossa for the lachrymal gland. 



THE ORBITS. 65 

(2.) A depression for the pulley of the Superior oblique muscle 
of the eye: 
FLOOR of the orbit. 

(1.) The infra-orbital groove, posteriorly. 
(2.) The infra-orbital canal, anteriorly. 

(3.) A depression, for the inferior oblique muscle of the eye. 
Inner wall of the orbit. 

(1.) A groove for the lachrymal sac. 

(2.) The crest of the lachrymal bone for the tensor tarsi muscle. 
Outer wall of the orbit. 

(1.) The orifices of the malar canals. 

(2.) A small spine for the attachment of the external rectus 
muscle of the eye. 
Superior external angle of the orbit. 

(1.) The articulation of the frontal and malar bones. 

(2.) The articulation of the frontal bone and the greater wing 

of the sphenoid bone. 
(3.) The sphenoidal fissure or foramen lacerum anterius. 
Superior internal angle of the orbit. 

(1.) A suture between the frontal bone and the lachrymal 

and ethmoid bones. 
(2.) The anterior ethmoidal canal. 
(3.) The posterior ethmoidal canal. 
Inferior external angle of the orbit. 
(1. The spheno-maxillary fissure. 

This transmits the infra-orbital vessels and nerves and 
the ascending branches of Meckel's ganglion. 
Inferior internal angle of the orbit. 

(1.) A suture, formed by the articulation of the superior max- 
illary and palate bones, below, with the lachrymal and 
ethmoid bones, above. 
Circumference of the orbit. 

(1 .) The stipra-orbital notcJi or foramen. 
APEX of the orbit. 

(1.) The optic foramen, which is formed by the two roots of 
the lesser wing of the sphenoid bone. To the upper 
root is attached the common tendon of the muscles of 
the eye. 
Each of these various points of interest has already been pre- 
viously described, in detail, in the accounts given of the special 
bones with which they are connected. It has not been deemed 
necessary therefore, to enter again into the purposes of many oi 



56 THE SKULL LN GENERAL. 

the points of interest and importance which are met with in the 
cavity of the orbit, a simple enumeration of them being sufficient. 

Muscles of the Orbit. 
Within the orbital cavity arise the following eight muscles : 
(i.) The External Rectus. 
(2.) The Internal Rectus. 
(3.) The Superior Rectus. 
(4.) The Inferior Rectus. 
(5.) The Superior Oblique. 
(6.) The Inferior Oblique. 
(7.) The Levator palpebral. 
(8.) The Tensor tarsi. 

Foramina of the Orbit. 
Each orbit has nine foramina, communicating with it, which 
may be thus enumerated : 

f Optic foramen. 

r r. . . . . 1 . / v j Sphenoidal fissure. 

Opening into the cranium (4K . r . c . ., ., , 

r & v M Anterior fronto-ethmoidal canal. 

I Posterior fronto-ethmoidal canal. 



The Orbit 
pre s e n t s 
nine 

mina, as 
follows : 



'J ( Supra-orbital foramen. 

' ^ Opening into the face (3) \ Infra-orbital foramen. 

( Malar foramen. 

Opening into the nose {f)\ Nasal duct. 

-Opening into the zygomatic fossa. {f)\ Spheno-m axillary fissure. 



Total, 9 

The supra-orbital foramen may be felt at the point of junction 
of the middle and the inner thirds of the supra-orbital margin, and 
a line drawn from that point to the interval between the bicuspid 
teeth of the upper and the lower jaws will cross the infra-orbital 
and the mental foramina. This is a valuable guide to these fora- 
mina, in case the division of any of the three branches of the fifth 
cranial nerve be demanded. 

The pulley of the superior oblique muscle may be felt by pres- 
sure being applied at the internal angular process of the frontal 
bone, and, in operations about the orbit, this process should be 
carefully avoided. 

The Nasal Fossae. 

The cavity of the nose is divided into two fossae, by a vertical 
septum situated in the median line of the face. 

Each nasal fossa is a narrow, irregularly shaped cavity, en- 
closed between the orbits, the superior maxillary bone, and the 
vertical septum, and, from below upwards, between the roof of the 
mouth and the anterior portion of the base of the skull. 



THE NASAL FOSSAE. 67 

Into the formation of each of the nasal fossae, nine bones enter, 
and fourteen into that of both, as shown by the following table : 

f Ethmoid. 
Mesial bones (4) \ l^*™*' 



The Nasal Foss^ have 14 | Vomer 

bones which enter into their " 



formation, viz, : 

*- 5 pairs of bones (10) 



Nasal. 

Superior maxillary, 

Lachrymal. 

Palate. 

Inferior turbinated. 



Total, 14 

Each of the nasal fossae presents for special examination the 
following component parts : A roof, a floor, an inner wall, an 
outer wall, an anterior opening, a posterior opening. 

The ROOF of each nasal fossa is narrow and forms an arch, and 
its longest axis lies in the antero-posterior direction. It presents 
the following points, which have been previously mentioned in 
the descriptions of the nasal, frontal, ethmoid and sphenoid bones, 
each of which participates in its construction. 

(1,) The anterior portion of the arch of the roof, which is 
formed by the nasal bone and the nasal spine of the 
frontal bone. 
(2.) The horizontal portion of the roof, which is formed by the 
under surface of the cribriform plate of the ethmoid 
bone. 
(3.) The posterior portion of the arch of the roof, which is 

formed by the body of the sphenoid bone. 
(4.) The opening into the sphenoidal sinuses which lies at the 

posterior portion of the roof. 
(5.) The olfactory foramina and the nasal slit. 
The FLOOR of each nasal fossa is concave, from side to side, 
and is formed by the palate processes of the superior maxillary 
bone and the palate bone. It possesses for examination the 
following points of interest : 

(1.) The suture between the two bones forming the floor. 

(2.) The upper orifice of the anterior palatine canal. 

(3.) The anterior nasal spine of the superior maxillary bone. 

(4.) The posterior nasal spine of the palate bone. 

(5.) The crest upon both the bones forming the floor, which 

articulates with the vomer. 
The INNER WALL of each of the nasal foss?e consists of the 
vertical septum which separates the two. It is formed principally 
of two bones, and, to a small extent, by five other bones, as is 
shown by the following enumeration : 



6S 



THE SKULL LN GENERAL. 



The INNER WALL of 
the nasal fossae is 
composed of seven 
bones, as follows : 



Principally by I Above and in front. 
two bones, •< 
viz. :...... f Below and behind. . 



By five bones, to a small extent, viz 



\ Perpendicular plate of the 
\ Ethmoid bone. 



f Rostrum of Sphenoid. 
Nasal spine of Frontal. 
Crest of Nasal. 
Crest of Palate. 
Crest of Superior Max- 
illary. 



In front, this septum has a triangular deficiency which is filled 
up with the so-called cartilage of the septum. The inner wall of 
the nasal fossae is frequently deflected from the median line to- 
wards one side, thus encroaching somewhat upon one of the 
cavities of the nose. 

The only points of interest perceived upon the surfaces of this 
septum, are the naso-palatine grooves, and vascular and nervous 
furrows. 

The OUTER WALL of each of the nasal fossae is formed by six 
bones, as follows : 



The OUTER WALL of 
the nasal fossa is 
composed of six 
bones, as follows : 



f Middle turbinated processes of the 
Ethmoid bone. 
fin its anterior portion. \ Internal surface of Superior Max- 
| illary bone. 
[Inferior turbinated bone. 
i Lachrymal bone. 
| Nasal process of the Superior Max- 

( ILLARY BONE. 

( Vertical plate of Palate BONE. 
k In its posterior portion. ■< Internal pterygoid plate of Sphe- 
( noid bone. 



" In the central porti 



This wall of the nasal fossa presents the following points of 
interest from above downwards: 

(i.) The superior turbinated bone of the ethmoid. 

(2.) The superior meatus of the nose, into which open the ori- 
fice of the sphenoidal sinus, the posterior ethmoidal 
sinuses, and the spheno-palatine foramen. This meatus 
consists of a short, irregular, longitudinal passage, and 
is situated at the upper and posterior portion of the 
nasal fossa. 

(3.) The middle turbinated bone of the ethmoid. 

(4.) The middle meatus of the nose, which is of greater length 
than the superior, and into which open the orifices of 
the antrum, the anterior ethmoidal cells and the 
frontal sinus. 

(5.) The inferior turbinated bone. 



THE NASAL FOSSAE. 



6 9 



(6.) The inferior meatus of the nose, the largest of the three 
passages, lies in close proximity to the floor of the 
nasal fossa, being situated between it and the inferior 
turbinated bone. It presents the interior or nasal 
opening of the lacrymal or nasal duct, and the upper 
opening of the anterior palatine canal. 

Openings of the Nasal Fossae. 

Besides the anterior and the posterior openings of the nasal 
cavities, there are eight other openings in each fossa, which are 
shown in the following table : 



Each Nasal Fossa 
has eight openings, 
which are situated 
as follows : 



Sphenoidal sinus. 
' In the superior meatus (3) \ Spheno-palatine foramen. 
Posterior ethmoidal cells, 
f Maxillary sinus, or antrum. 
T ,, .,,, i , J Anterior ethmoidal cells. 

In the middle meatus (3K -w *. i \ „ +u -u <.u • r j- 
w ) r 1 rontal sinus, through the mfundi- 

• [ bulum. 

w T ,, . r . . , s. ( Lower opening of the nasal duct. 

In the inferior meatus (2) \ AT \ \ .. s , 

v ' I Naso-palatme canal. 

Total, 8 

The frontal sinuses, which communicate with the nasal fossae, 
have an important relation to the operation of trephining for 
wounds of the frontal region. They do not exist in children, 
since the tables of the skull do not begin to separate until the 
age of puberty. The absence of marked prominences over the 
region of these sinuses does not necessarily indicate their small 
size, since the sinuses are often formed at the expense of the inner 
wall of the cranium. Animalculae and small insects have been 
known to obtain an entrance into the cavity of the frontal sin- 
uses, through the nose. 

The external aperture of the nose, in the living subject, lies on 
a lower plane than the floor of the nasal cavity, so that the nose 
must be pulled upwards, if a full view of the nasal cavity is to be 
obtained from in front. The inferior turbinated bone can be per- 
ceived only by dilating the ala of the nose. 

Since the cavity of the nasal fossa is narrower in the transverse 
diameter, even in the inferior meatus, than in the perpendicular 
direction, any instrument introduced to remove foreign growths 
of extraneous bodies should be opened in the longest axis of the 
inferior meatus. 



;o 



THE SKULL IN GENERAL. 



Sup. Maxil- 
lary. 



Ethmoid. 




TABLE OF SUMMARY 
Frontal 

Ethmoid 

Sphenoid 

Vomer 

Sup. Maxillary.. 

Nasal 

Lachrymal 

Malar , / 

Palate 

Inf. Turbinated 




Orbit. 

7 bones. 



Nasal Foss 
9 bones. 



This diagram is intended to illustrate the formation of the 
orbital and nasal cavities, and also the various articulations of the 
ethmoid and the superior maxillary bones. 

The lines connecting the various bones to the parts designated 
at the corners of the diagram show, upon the left hand of the 
page, the formation of the nasal cavities and the orbits, and, 
upon the right hand, the articulations of the ethmoid and the 
superior maxillary bones. 



THE LATERAL REGION OF THE SKULL. 

The lateral regions of the skull present for examination por- 
tions of the temporal, parietal, sphenoid, frontal, malar and in- 
ferior maxillary bones. It also presents three important regions 
which have received special names, and which are called, respec- 
tively, the temporal fossa, the zygomatic fossa and the spheno- 
maxillary fossa. 

To ascertain the relative proportions of the frontal, the pari- 
etal, and the occipital regions of the skull, pass a thread from one 
external auditory meatus to that of the opposite side, across the 
frontal, the parietal, and the occipital eminences, respectively, and 
record their measurements. 

The three principal bony points upon the lateral aspect of the 
skull are, 

(i.) The zygomatic arch and the upper portion of the ramus of 
the jaw, the former of which arches over the tem- 
poral, zygomatic and sphenomaxillary fossae. 
(2.) The external auditory meatus, which is the external orifice 
of the bony canal leading to the drum membrane of 
the tympanum. 



LA TERAL REGION OF THE SKULL. 



n 



(3.) The mastoid process of the temporal bone which is situated 
at the posterior portion of this region. 

Temporal Fossa. 

This fossa is formed by parts of the following five bones. 

(1.) The frontal bone. 

(2.) The great wing of the sphenoid bone. 

(3.) The temporal bone. 

(4.) The anterior inferior angle of the parietal bone. 

(5.) The malar bone. 
It is deeply excavated in its anterior and lower portions, but 
is comparatively shallow in its superior and posterior portions. 
It is bounded as follows : 



The Temporal fossa 
is bounded as fol--{ 
lows : 



Above by the \ Temporal ridge. 

{Line of the zygomatic arch. 
Pterygoid ridge upon the greater 
wing of the Sphenoid bone. 
I Malar bone. 

In front by the •< Frontal bone. 

( Great wing of the Sphenoid. 
Behind by the «( Temporal ridge. 

This fossa is traversed by six sutures, viz. : 

(1.) The spheno-malar. 

(2.) The spheno-frontal. 

(3.) The spheno-parietal. 

(4.) The squamo-sphenoidal. 

(5.) The fronto-parietal, or the coronal. 

(6.) The squamo-parietal. 
The temporal fossa becomes continuous, at its lower border, 
viz., at the line of the zygomatic arch and the pterygoid ridge, 
with the zygomatic fossa. It contains the temporal muscle and 
the deep temporal vessels. 

Zygomatic Fossa. 

The zygomatic fossa is an irregular and imperfectly closed 
space, the incomplete walls of which are thus formed. 

In front by the j^laryW^ ^ ^^^ ""^ 

Internally by the. . 



The Zygomatic fossa 

is bounded as fol- J Above by the. 
lows : 



Externally by the. 
Below by the 



External pterygoid plate of the 
Sphenoid bone, 
f Under surface of the great wing of 
J the Sphenoid bone. 
I Squamous portion of the Temporal 
[_ bone. 
( Zygomatic arch. 
} Ramus o( lower jaw . 
( Areolar border of the Inferior Max- 
) illaiy bone. 



7 2 



THE SKULL LN GENERAL, 



This fossa communicates with the temporal fossa, beneath the 
zygomatic arch, and also with the orbit and the sphe no-maxillary 
fossa. The following table illustrates the channels of communi- 
cation between these three cavities. 

"Beneath the zygomatic arch with the*{ Temporal fossa. 



The Zygomatic fossa 



Through the , sphenomaxillary fis- ^ 
sure with the , 



communicates | Through the pterygo-maxillary fis- j Spheno-maxillary 

[_ sure with the ( FOSSA. 

The spheno-maxillary fissure is a large sized space situated 
between the sphenoid and malar bones, on the outside, and the 
superior maxillary and palate bones, on the inside of the opening. 
The malar bone, however, does not always enter into its formation. 

It joins at a right angle with the pterygo-maxillary fissure, 
which exists between the superior maxillary bone and the ptery- 
goid process of the sphenoid bone, and thus affords an opening 
into the spheno-maxillary fossa. 

This fissure is the means of communication between the orbit, 
on the one hand, and three cavities, viz., the temporal, zygomatic 
and the spheno-maxillary fossae, on the other. 

It transmits the infra-orbital artery, the superior maxillary 
nerve and its orbital branches, and the ascending branches of 
Meckel's ganglion. 

This fissure is horizontal in its direction, and is situated at the 
outer and back part of the orbit. 

The pterygo-maxillary fissnre is situated between the tuber- 
osity of the superior maxillary bone and the pterygoid process of 
the sphenoid bone. 

It joins the spheno-maxillary fissure, at a right angle, and trans- 
mits the terminal branches of the internal maxillary artery, in its 
passage from the zygomatic fossa to the spheno-maxillary fossa. 

It is vertical, in direction, and is rather an elongated interval 
between the bones mentioned above, than a true fissure. 

Spheno-maxillary Fossa. 

The space, called by this name, is a narrow and elongated 
cavity, triangular in form, comprised between the pterygoid pro- 
cess of the sphenoid bone and the tuberosity of the superior max- 
illary bone. 

It is bounded as follows : 

r Above by the \ U * d f" su ^ ce of the bod ? of the 

, „ ( bphenoid bone. 

The Spheno-maxillary \ t , . , , , . .„ , 

FOSSA is bounded asj In f ront b ^ the "^ Su P erior maxillary bone. 

follows : i Behind bv the \ Ptei 7g oid process of the Sphenoid 

y / bone. 

Internally by the . . . \ Vertical plate of the Palate bone. 



BASE OF THE SKULL. 73 

This fossa has three fissures which terminate in it, viz., the 
sphenoidal, the spheno-maxillary, and the pterygo-maxillary 
fissures. 

It communicates also with three fosses and two cavities, which 
may be thus enumerated : 

( Orbit. 

The three fossae are : ■< Nasal cavity. 

( Zygomatic. 

The two cavities are : j ^caf ' 

It has five foramina which open into it, viz. : 

{Foramen rotundum. 
Vidian canal. 
Pterygo-palatine canal. 

*' M™ E v e F os"1 °» «« «™» -« • - W i Sphenopalatine foramen. 

...hi , • / v ( Superior orifice of the poster- 

(^ At the lower portion. . (1) < 



ior palatine canal. 



Of these, the foramen rotundum opens into the cranium, the 
vidian canal opens into the foramen basis cranii, the sphenopala- 
tine foramen opens into the nasal fossa, the posterior palatine 
canal opens into the roof of the mouth, and the pterygo-palatine 
canal opens into the upper portion of the pharynx. 

Occasionally accessory palatine foramina are present at the 
lower portion of this fossa, in addition to the opening of the pos- 
terior palatine canal. 

THE UNDER SURFACE OF THE BASE OF THE 

SKULL. 

The under surface of the skull is bounded from before back- 
ward by the following bony margins : 

In front by the. ... J Alveolar . arch and the teeth of the 
J J I upper jaw. 

f Lower border of the Malar bone. 
The Base of the Skull J .. . . J Zygomatic arch. 

is bounded as follows :\ Laterally by trie ^ Imaginary line from the zygoma to 

[_ the mastoid process. 

V Behind by the j Sn g^ CU1 ' ved line ° f the 0cci P ital 

From before backwards, the base of the skull may be said to 
consist of five distinct regions. 

A. The roof of the mouth. 

B. The posterior aperture of the nasal cavity. 

C. The under surface of the basilar process. 

D. A quadrangular space on either side of the basilar 

process. 

E. The under surface of the occipital bone. 



74 



THE SKULL IN GENERAL. 



Each of these regions at the base of the skull contains points 
deserving of enumeration and they will therefore be individually 
described. 

A. Roof of the Mouth. 

This portion of the base of the skuII is formed by the palate 
processes of the two superior maxillary bones and by the horizon- 
tal plates of the two palate bones. It is bounded, at its circum- 
ference, by the alveolar border of the two superior maxillary 
bones. 

It is concave in form, uneven upon its surface, and presents a 
crucial suture, which indicates the four bones which compose it. 

It presents, from before backwards, the following points of 
interest. 

(i.) The lower openings of the anterior palatine canals. 

(2.) The foramen of Stenson, in the mesial line. 

(3.) The foramina of Scarpa for the naso-palatine nerves. 

(4.) The posterior palatine foramina. 

(5.) The accessory palatiiie foramina for the small palatine 
nerves. 

(6.) A transverse ridge of bone for the aponeurosis of the 
tensor palati muscles. 

B. The Posterior Aperture of the Nares. 

These large openings (one on either side of the mesial line) 
are bounded separately as follows : 

( Horizontal plates of the Palate bone. 

Below by the •< Posterior nasal spine of the Palate 

( bone. 

{Internal pterygoid plates of the 
Sphenoid bone. 
Hamular process of Sphenoid. 
Internally by the . . . \ Vomer. 
Above by the \ Body of the Sphenoid bone. 



The POSTERIOR NARES 

are bounded as fol- 
lows : 



These apertures allow of communication between the nasal 
cavities and the upper portion of the pharynx. Superiorly, there 
is perceived at the margin of these apertures, near to the body of 
the sphenoid bone, two points deserving &f mention, viz. : 

(1.) The expanded alee of the vomer. 

(2.) The pterygo palatine canals. 

C. Under Surface of the Basilar Process. 

The basilar process of the occipital bone lies at about the cen- 
tre of the base of the skull, in the mesial line. It is situated 
between the foramen magnum and the posterior aperture of the 



BASE OF THE SKULL. 



75 



nares, and is slightly less than one inch in length. It presents in 

the median line of the bone, the two following points of interest. 

(i.) The pharyngeal spine, to which is attached the median 

raphe and the superior constrictor muscle of the 

pharynx. 

(2.) Two rough depressions, upon each side of the pharyngeal 

spine, for the attachment of the rectus capitis anticus 

major and the rectus capitis anticus minor muscles of 

the respective sides. 

D. The Quadrangular Spaces. 

These spaces at the base of the skull are formed by the under 
surface of the occipital bone, by the squamous and petrous por- 
tions of the temporal bone, and by the greater wing of the sphen- 
oid bone. They are situated upon each side of the basilar pro- 
cess of the occipital bone, and are each bounded as follows. 

In front, by a line extending from the base of the pterygoid * 

process to the root of the zygoma. 
Externally, by a line from the root of the zygoma to the mas- 
toid process. 
Behind, by a line from the mastoid process to the anterior 

extremity of the condyles of the occipital bone. 
Internally, by a line from the condyle to the base of the 

pterygoid process. 
Its four angles correspond, therefore, to the four following 
points, viz. : 

(1.) Condyle of the occipital bone. 
(2.) Base of the pterygoid process. 
(3.) Anterior root of the zygomatic process. 
(4.) Tip of the mastoid process. 
This quadrangular space is divided into two parts by an 
oblique line directed from before backwards and outwards. This 
line extends from the pterygoid process to the mastoid process, 
and, in its course, it includes the following points of interest 
which will here be simply enumerated, as their function has 
already been given in previous pages of this volume. 
(1.) The foramen lacertim medium. 
(2.) A roughened surface for the attachment of the levator 

palati and the tensor tympani muscles. 
(3.) The inferior orifice of the carotid canal. 
(4.) The vaginal process of the temporal bone. 
(5.) The styloid process of the temporal bone. 
(6.) The stylo-mastoid foramen. 



;6 



THE SKULL IN GENERAL. 



In front and to the outer side of this diagonal line are found 
the following points of interest, in their order from before back- 
wards and outwards. 

(i.) The foramen ovale. 

(2.) The foramen Vesalii. 

(3.) The foramen spinosum. 

(4.) The spinous process of the sphenoid bone. 

(5.) The opening for the Eustachian tube (osseous portion.) 

(6.) The opening for the canal of the tensor tympani muscle. 

(7.) The glenoid fossa of the temporal bone. 

(8.) The Glaserian fissure, dividing the glenoid fossa into two 
portions. 

Behind and to the inner side of the diagonal line, are per- 
ceived also the following points of special interest. 

(1.) The jugular fossa. 

(2.) The jugular foramen, or foramen lacerum posterius, 

(3.) The jugular process of the occipital bone. 

(4.) The anterior condyloid foramen. 

(5.) The posterior condyloid foramen. 

(6.) The foramen for Jacobsons nerve. 

(7.) The foramen for Arnold's nerve. 

(8.) The opening of the aquceductus cochlea?. 

E. The Under Surface of the Occipital Bone. 

This comprises the remaining portion of the base of the skull. 
It exhibits the following points deserving of special enumeration. 

(1.) The condyles of the occipital bone. 

(2.) The jugular processes of the occipital bone. 

(3.) The anterior condyloid foramina. 

(4.) The posterior condyloid foramina or fossa. 

(5.) The external occipital crest. 

(6.) The superior curved line of the occipital bone. 

(7.) The inferior curved line of the occipital bone. 

(8.) The external occipital protuberance. 

For a detailed description of the parts mentioned in the pre- 
ceding pages see the description of the individual bones of the 
cranium and the table of cranial foramina. 



A TA1E INTERIOR OF THE CRANIUM, 
NSMIT. 



THROUGH THE VARIOUS FORAMINA. 



bmbrane of the nose to the superior longitudinal sinus, and some- 
SINGLE, Ol lodges also a fold of the dura mater. 

vertebral arteries, and the spinal accessory nerves. 



jlal artery. 
IN nasal branches of the ethmoidal arteries. 
ANTERIO erve. 

5 pa 



the ophthalmic division of the fifth, and the sixth cranial nerves, 
the opthalmic vein, a branch of the lachrymal artery, and some- 
orbital branches of the middle meningeal artery, and a process of 



in "h of the trifacial or fifth en 



anial nerve. 



f Santorini. 
MIDDLEjerve, or third branch of the fifth cranial nerve, the lesser petro- 
j'tery, a branch of the internal maxillary, 
g _Jal veins, and filaments of the sympathetic from the cavernous plexus. 
1 the large petrosal nerve, and a meningeal branch from the as- 



dle meningeal artery, which anastomoses with the stylo-mastoic 
cular. 



lory artery, a branch of the basilar. 
IN i the dura mater. 

pinal accessory nerves ; the internal jugular vein, and meningeal 
j^eal and occipital arteries. 
POS I EKI(jj cat j on between the occipital vein and lateral sinus, and occasion- 
cipital, called the mastoid artery, which ramifies in the dura mater. 
6 p ranch from the ascending pharyngeal artery. 

ommunication with the vertebral vein and lateral sinus. 



The ie, called the Parietal, on each side of the sagittal sature, transmits 
a small veinium and the foramen magnum. Of the remaining 3S, 5 pairs are 
found in the wards. 

The rjte the Foramina of exit of branches. 



* Frequ 



A TABLE REPRESENTING THE FORAMINA COMMUNICATING WITH THE INTERIOR OF THE CRANIUM, 

AND THE ORGANS WHICH THEY TRANSMIT. 



FORAMEN. 

r I. Anterior Fossa. 

I I. Foramen Caecum 

SINGLE, OR MESIAL. X n posTERIOR FossA 

( 2. Foramen Magnum 


PARTS PASSING THROUGH THE VARIOUS FORAMINA. 

Transmits a small vein from the lining membrane of the nose to the superior longitudinal sinus, and some- 
times one from the frontal sinus, and lodges also a fold of the dura mater. 

Medulla oblongata and its envelopes, the vertebral arteries, and the spinal accessory nerves. 


/ i. Ethmoidal Fissure 

IN THE I 2. Ulfaclurv Kuiamina 

ANTERIOR FOSSA. X 3- Anterior Ethmoidal Canal (Fronto-Ethmoidal) 

. j 4. posterior Ethmoidal Canal (Fronto-Ethmoidal) 

5 Pa " S ' ' 5- Optic Koramcn 


The nasal nerve, and the anterior ethmoidal artery. 

Filaments of the olfactory nerve and the nasal branches of the ethmoidal arteries. 

Anterior ethmoidal artery and the nasal nerve. 

Posterior ethmoidal artery and vein. 

Optic nerve and the ophthalmic artery. 


IN THE 


1. Korani tale (Sphenoidal Kissure Spheno-Ki'on- 

lal foramen) 

2. Foramen Rotundum 


The third, fourth, the three branches of the ophthalmic division of the fifth, ami the sixth cranial nerves, 
and filaments of the sympathetic ; the oplhalmic vein, a branch of the lachrymal artery, and some- 
times the lachrymal artery itself, the orbital branches of the middle meningeal artery, and a process of 
the dura mater. 

Superior maxillary nerve, or second branch of the trifacial or fifth cranial nerve. 


MIDDLE FOSSA. 
8 pairs. 


3. *Foramen Vesalii 

( Foramen Ovale 

5. Foramen Spinosum 

6. Foramen Lacerum Medium (Spheno-Petrosal, Foramen basis 

7. Small Foramen 

S. Hiatus Fallopii 


A small vein, one of the emissary veins of Santorini. 

The two roots of the inferior maxillary nerve, or third branch of the fifth cranial nerve, the lesser petro- 
sal nerve, and the small meningeal artery, a branch of the internal maxillary. 

Middle meningeal artery, the two meningeal veins, and filamentsof the sympathetic from the cavernous plexus. 

Internal carotid artery, the carotid plexus, the large petrosal nerve, and a meningeal branch from the as- 
cending pharyngeal artery. 

Lesser petrosal nerve. 

Large petrosal nerve, a branch of the middle meningeal artery, which anastomoses with the stylo-mastoid 
artery, a branch of the posterior auricular. 


IN THE 

POSTERIOR FOSSA. 
t> pairs. 


2. Aqueduct'oi thVvestibule 

:erum Posterius (Oi 1 ipito 

4 *Mastoid 



6. *Posterior Condyloid 


Facial and auditory nerves, and the auditory artery, a branch of the basilar. 

A small artery and vein, and a process of the dura mater. 

Glossopharyngeal, pneumogastric, and ijpinal accessory nerves; the internal jugular vein, and meningeal 
branches from the ascending pharyngeal and occipital arteries. 

A small vein which establishes a communication between the occipital vein and lateral sinus, and occasion- 
ally a small arterial twig from the occipital, called tin in istoid artery, which ramifies in the dura mater. 

The hypoglossal nerve and a meningeal branch from the ascending pharyngeal artery. 

Posterior condyloid vein, establishing a communication with the vertebral vein and lateral sinus. 



I he number of foramina communicating with the interior of the cranium varies from 36 to 42 : 2 at vertex, rest at base. Of these, one, called the Parietal, on each side of the sagittal sature, transmits 

•' s|ll ' ll > vein and somel smali artery, a branch of the occipital. Of the remaining 40, 2 are in the mesial plane : viz., the foramen caecum and the foramen magnum. Of the remaining 38, 5 pairs are 

ttttd 111 the anterioi fossa, in the middle fossa, and 6 in the posterior fossa. The foramina are arranged in regular order from before backwards. 

Ihe names print) i 1 red indicate the Foramina through which one or more of the Cranial nerves pass ; those underlined in red indicate the Foramina of exit of branches. 



''.ciuendv nbsent-tlius causinj; v« 



SKELETON OF THE TRUNK 



THE VERTEBRAL COLUMN. 79 

SKELETON OF THE TRUNK. 

The skeleton of the trunk may be sub-divided into three parts, 
as follows : 

The VERTEBRAL COLUMN. 
The THORAX. 
The BONY PELVIS. 

THE VERTEBRAL COLUMN. 

The true vertebral column is composed of twenty-four bones, 
placed one above the other, and extends from the occipital bone 
above, to the sacrum below. These bones are termed the true 
vertebrce, in contradistinction to the sacrum and the coccyx, which 
are termed the false vertebrce. 

The vertebrae are named in numerical order, from above down- 
wards, or, in other words, from the occipital bone to the sacrum, 
according to the region in which they are situated. Hence the 
name of any particular vertebra must be expressed by two adjec- 
tives ; one indicating the region in which it is situated, and the 
other the place it occupies in that region. 

In the cervical region, there are three vertebrae, which, in addi- 
tion to the numerical, have also special names, viz., the first cer- 
vical or atlas, the second cervical or axis, and the seventh cervical 
or the vertebra prominens. 

Before proceeding to the description of the vertebrae, it will be 
well to consider the nature and function of this important portion 
of the skeleton, which may be thus stated : 

1st. It provides a column to sustain the weight of the head 
and trunk. 

2d. It affords a canal to lodge an important organ, the spinal 
cord. 

3d. It affords, by means of numerous intervertebral foramina, a 
means of communication between the spinal cord and the various 
parts of the body, through the spinal nerves. 

4th. It affords, by means of its spinous and transverse pro- 
cesses, a system of levers upon which the muscles of the trunk 
may act. 

5th. As the column must be flexible and elastic in order to 
allow of the various motions of the trunk, it must consist of a 
number of pieces united together by means of cartilage and liga- 
ments. 

6th. In order to afford greater security to the connection be- 
tween important parts than would be ensured by ligaments only, 



8o 



SKELETON OF THE TRUNK. 



the bones are also firmly held in position by means of the articulai 
processes. 

The anatomy of the vertebrae will be considered in this vol- 
ume under the following heads : 

(A.) General characteristics of a Vertebra. 

(B.) Regional characteristics of Vertebra. 

(C.) Individual characteristics of Special Vertebrae. 

(D.) The vertebral column as a whole. 

(A.) 

GENERAL CHARACTERISTICS OF THE VERTEBRAE. 

A vertebra possesses the following component parts, which 
will each require a special description. 



(i.) A Body. 

(2.) A Spinal foramen. 

( A spinous process. 
(3.) Seven processes. < Four articular processes. 

( Two transverse processes. 
(4.) two pedtcles. 
(5.) Four notches. 
(6.) two laminae. 



Diagrammatic Plan of a Vertebra. 

Spinous process. 



Lamina (2.) 

Articular process, . . , . .(3.) 

Transverse process (4.) 

Pedicles and notches. . . .(5.) 




(2.) . Lamina. 

(3.) Articular process 

(4.) .... Transverse process 
(5.). . .Pedicles and notches. 



(i.) The Body. 

This portion of each vertebra presents for examination the 
following points : 

(1.) An upper surface. 

(2.) A lower surface. 

(3.) An anterior surface. 

(4.) A posterior surface. 



THE VERTEBRAL COLUMN. 8 1 

is convex, from side to side. 
The anterior surface . . \ is slightly concave, from above downwards. 

has small foramina upon it for the transmission of blood-vessels 

iis concave, from side to side, 
is flat, from above downwards, 
has one or more apertures for the venae basis vertebrarum, 
{is concave, 
is roughened for the intervertebral fibro-cartilage., 
is bordered, at its circumference, by a prominent rim of bone. 
( is concave. 
The under surface. ... sis roughened for the intervertebral fibro-cartilage. 

( is bordered, at its circumference, by a prominent rim of bone. 

(2.) The Spinal Foramen. 

The spinal foramen may be rudely compared to a pentagonal 
arch, the base of which corresponds to the posterior 
surface of the body of the vertebra, the piers of which 
are the pedicles, and the vault of which is formed by 
the laminae. 

(3.) The Spinous Process. 

This projects backwards from the point of junction of the 
laminae. 

(4.) The Transverse Processes. 

These are two in number, one on each side. They project 
outwards from the sides of the arch. 

(5.) The Articular Processes. 

' These are four in number, two on each side, and are called, 
from their position on the vertebra, the superior and 
the inferior. They are usually situated at the point of 
junction of the pedicles with the laminae, but they vary. 
The articular processes also vary as to the direction to- 
wards which their surfaces are directed. The superior 
ones usually look backwards and the inferior ones look 
forwards. 

(6.) The Pedicles. 

The pedicles project backwards and slightly outwards from the 
point of junction between the anterior and posterior 
surfaces of the body. They are scooped out, on their 
upper and lower borders, so as to form the notches, 
which are generally deeper upon the lower than upon 
the upper border. These notches contribute to the 
formation of the intervertebral foramina. 

(7.) The Notches. 

These notches, when the vertebrae are superimposed upon 
each other, form the so-called intervertebral foramina, 
through which the spinal nerves escape, and vessels 
enter. 



82 skeleton of the trunk. 

(8.) The Lamina. 

These plates of bone are broad and flattened. They complete 
the arch and help to form the spinal foramen. They 
are roughened, on their upper and lower borders, for 
the attachment of the ligamentum subflava. 

(B.) 

REGIONAL CHARACTERISTICS OF THE 
VERTEBRA. 

Cervical Vertebra. 

The cervical vertebrae are the smallest and the lightest of any 
of the three regions of the spine. They present for examination 
all the points designated as common to the vertebrae in general, 
with the exception of the atlas or 1st cervical vertebra and the 
axis or 2nd cervical vertebra, which will be described under the 
special vertebrae. The peculiarities which are the means of de- 
termining their situation, if examined apart from other vertebrae, 
are as follows : 

Small and broad from side to side. 
The upper surface is concave from side to side, 
being surmounted laterally by the projecting 
laminae, and its greatest diameter is the trans- 
-r> n verse one. 

The under surface is convex and prolonged 
downwards in front, so as to overlap the ad- 
joining vertebra. 
The anterior surface is on a lower level than the 
posterior. 
PEDICLES. These arise from the lower part of the body. 
NOTCHES. The superior notches are the deepest. 
LAMIN/E. The laminae are long and narrow. 
Spinal Foramen. The spinal opening is large and tri- 
angular. 
SPINOUS PROCESS. This process projects horizontally back- 
wards. 
It is short, bifid, and grooved on its lower 
surface. 
TRANSVERSE PROCESS. This process is short, bifid, and grooved 

upon its upper surface. 
It is perforated, at its base, by the 
vertebral foramen. 



REGIONAL CHARACTERISTICS OF VERTEBRAE. 83 

Are situated outside of the pedicle. 
Lie in front of the articular process. 
ARTICULAR PROCESSES. The two superior look upwards and 

backwards. 
The two inferior looks downwards 
and forwards. 
The distinctive characteristic of a cervical vertebra is the pres- 
ence of a foramen at the base of the transverse process, called the 
vertebral foramen, since it transmits the vertebral artery and vein 
and the vertebral plexus of the sympathetic system of nerves. 

Each transverse process of the cervical vertebra is formed by 
two roots ; the anterior root arises from the sides of the body and 
corresponds to the ribs which spring from the dorsal vertebra ; 
the posterior root arises from the junction of the pedicle with the 
lamina and corresponds to the transverse process of the dorsal 
region. 

The extremities of these two roots produce the bifid appear- 
ance of the transverse process of the cervical vertebra and form 
the so-called anterior and posterior tubercles of these processes, to 
which many of the muscles of the neck are attached. 

Dorsal Vertebras. 

The dorsal vertebrae are of intermediate size, being larger than 
those of the cervical and smaller than those of the lumbar region. 
Their distinguishing characteristics may be thus enumerated. 
Is heart-shaped. 
BODY. Is thicker behind than in front. 

Has two demi-facets on each side, for the articu- 
lation of the head of the ribs. 
PEDICLES. These arise from the upper part of the body. 
NOTCHES. The inferior notches are the broadest and deepest. 
Laminae. The laminae are short and broad. 
SPINAL Foramen. The spinal opening is small and round. 
SPINOUS PROCESS. This process is long, triangular and oblique 

in its direction. 
TRANSVERSE PROCESSES. These processes are long and thick. 

They are directed obliquely out- 
wards and backwards. 
They are situated behind the ar- 
ticular processes. 
They are situated also behind the 

pedicles. 
Their extremity is enlarged and 



8 4 



SKELETON OF THE TRUNK. 



Articular processes. 



Lumbar Vertebrae. 



has a facet on its anterior sur- 
face for the attachment of the 
tubercle of the rib. 
In a few of the lower dorsal ver- 
tebrae, upon the posterior surface 
of this process, are found three 
tubercles called the external, i?i- 
ferior and superior. 
The two superior look backwards 

and slightly outwards. 
The two inferior look forwards and 
slightly inwards. 



These vertebra are of very large size. Their chief characteristics 
may be thus enumerated : 

Is very large. 

Is broadest in its transverse diameter. 
Is thicker in front than behind. 
The pedicles are thick and strong. 
They arise from the upper portion of the body. 
The inferior notches are the deepest and broadest. 
The laminae are short, thick and very broad. 



Body. 

Pedicles. 

Notches. 
Laminae. 

Spinal FORAMEN. The spinal opening is triangular in shape. 

Is larger than in the dorsal region but 

smaller than in the cervical region. 

SPINOUS PROCESS. This process is thick, is quadrilateral in 

shape, and ends in a rough, vertical 

border. 

TRANSVERSE PROCESSES. These processes are lo7tg and slender. 

They are directed horizontally out- 
wards. 
They are situated in front of the 

articular processes. 
They are also located behind the 

pedicles. 
On the posterior surface of each, 
near its base, is a small tubercle 
called the accessory tubercle, which 
points downwards and inwards. 
ARTICULAR PROCESSES. These processes are very thick and 

strong. 
They are placed vertically. 



PECULIAR VERBETRM. 



85 



The two superior 'look backwards and 

inwards and are concave. 
The ^ze/0 inferior look forwards and 
outwards and are convex. 

Table of Contrast of the Cervical, Dorsal and Lum- 
bar Vertebrae. 



Cervical. 
f Small in size. 



Dorsal. 
Intermediate in size. 



Body.. 



Pedicles.. 



J Upper surface concave, j Heart shaped. 
' t Under surface convex. ] Ti " 
" ! Hi 



Lumbar. 
f Large, in point of 

size. 
J Very broad. 
Thickest behind. 1 Thickest in front. 

| Anterior border round- j Has 2 demi-facets on j 
(^ ed off. [ each of its sides. (_ 

Arise from lower part \ From upper part of j From upper part of 
of body. \ body. \ 

Notches. . . . \ Superior the deepest. \ Inferior the deepest. 

Laminae. , . ,\ Long and narrow. \ Short and broad. 



body. 

\ Inferior the deepest. 
■{ Short, broad, thick. 



Spinal open 

ING, 



X Large and triangular. ■] Small and round. \ 

{ Directed horizontally f 
| backwards. I Directed obliquely. 

Spinous pro- J Short and bifid. 

cess < 

Grooved inferiorly. 

Shoit and bifid. 



Triangular and in- 
termediate in size. 

Directed backwards, 
j Thick and quadri- 
lateral. 
Rough vertical bor- 
der. 



Transverse 
processes. 



Grooved superiorly. 

Vertebral foramen at 
base. 

Outer side of pedicle. 

In front of artic, pro- 
cess. 



Long and triangular. 

| Ends in a single tuber- 
[ cle. 

Long, thick and ob- f Long, slender, hori- 

lique. 
Extremity enlarged. 
Facet on ant. surface. 



Behind the pedicle. 
Behind artic. process. 



r Superior look B and U. { Superior look B and O. 
Inferior]ook D and F. I Infetiorlook F and I. 



Articular j 
processes. 1 



Form two small verti-J Form 
cal columns. 1 which 



zontal. 

Accessory tuber- 
"| cle " present. 
I Behind pedicle. 
| In front of artic. 
[_ process. 

" Superiorlook B and I* 
Inferiorlook F and O* 
Superior are concave 



vertical. 



two columns . and widely separat- 
or nearly j ^ A 



ed. 
j Inferior are convex 
| and nearer together 
1^ than the superior. 



(C) 

CHA -ACTERISTICS PECULIAR TO CERTAIN VER- 
TEBRA. 

In the different parts of the vertebral column, there are verte- 
brae which, in addition to general regional characters, possess indi- 
vidual characteristics, by which they may be distinguished from 
all the rest. These vertebrae may be thus enumerated : 

In the cervical region, (3), atlas, axis and vertebra prominens. 

In the dorsal region, (5), ist,9th, 10th, nth, 12th. dorsal ver- 
tebrae. 

In the lumbar region, (1), 5th. lumbar vertebrae. 



86 



SKELETON OF THE TRUNK. 



THE ATLAS. 



This bone presents for examination . 



2 arches, 



\ Anterior. 
1 Posterior. 
2 lateral masses. 
[A spinal foramen. 



It lies between the occipital bone and the axis. It corre- 
sponds to the first cervical vertebra but has received a special 
name from its function (supporting the globe of the head). The 
following points of anatomical interest pertaining to this bone are 
deserving of notice ; 



The Anterior Arch presents 



The posterior arch presents 



f (i) Convex in shape. 

r (l.) An anterior surface \ < 2 > A t ^ U in its centre, for 
the attachments of ligaments 
[ and the longus colli muscle, 
f (i) Concave in shape. 
(2.) A posterior surface \ &) ^\™al facet in its centre, 
r tor the articulation of the 

[_ odontoid process of the axis. 
(3.) An upper and lower border. To which are at- 
tached the deep occipito-atloid and the deep anterior 
atlo-axoid ligaments. 



j Superior intervertebral artery, 
\ Inferior intervertebral artery. 
(2.) A tubercle for the rectus capitis posticus minor. 



(1.) Grooves for the. 



"(i.) Four tubercles. 



The LATERAL MASS- 
ES present 



I 2 Inferior^' j for the transverse ligament. 

(2.) 2 transverse processes, which are large, and are perforated by 
a large foramen (vertebral.) 

j (3.) 2 Sup. Articu- j Large, oval, concave. 

lar surfaces \ Looking upwards, inwards and backwards. 



(4.) 



2 Inf. Artie, 
surfaces . . . 



Smaller, flat and circular. 
Looking downwards and inwards. 



The spinal foramen is large and is divided, by the transverse 
ligament, into an anterior and posterior space. The anterior space 
lodges the odontoid process of the axis, and the posterior space 
lodges the upper portion of the spinal cord and its membranes. 

In the atlas, the anterior arch forms about one-fifth only, while 
the posterior arch comprises about two-fifths of the circumference 
of the entire bone. 

The grooves upon the posterior arch, for the passage of the in- 
ter-vertebral arteries, lie upon its anterior and under surfaces, and 
are occasionally complete foramina. 

The superior articular surfaces, by their shape and direction, 
allow of the nodding motion of the head, while the inferior articu- 
lar surfaces allow of a movement of rotation only. 



THE AXIS. 87 



/ft. 



.) The body. 
The Superior set rest upon \ (2.) The pedicles. 

(3.) The transverse processes. 
ARTICULAR SURFACES. . \ They are large, flat and circular. 

They look uptuards and outwards. 
J The Inferior set are smaller in size and look downwards 
(_ and forwards. 

The point of attachment of the check ligaments to the odon- 
toid process of the axis is marked by two rough impressions, upon 
its sides, near to its apex. 

The two tubercles, produced by the bifid condition of the spi- 
nous process of the axis, serve for the attachment of the muscles 
which rotate the head upon the spine. 

THE AXIS. 
The axis or the second cervical vertebra is so called from its 
odontoid process which allows of movement of the atlas upon it. 
It presents the following points of interest : 

Body. This is much thicker in front than behind. 
It is triangular in shape. 

It is prolongued downwards so as to overlap the third 
cervical vertebra. 
The Odontoid process (so called from its resemblance to a 
tooth.) 

IC Gives attachment to the occipito-odontoid 
f (i.) An apex . . . < ligament, and, laterally, to the check liga- 
( ments (lateral occipito-odontoid.) 
I This artictilates with the Atlas, in front- 

This process presents, -j ( 2 .) a body X Behind, it lies in relation with the trans- 

( verse ligament. 
/ w , j This is constricted into a channel for the 

V 1 ?"' \ transverse ligament. 

PEDICLES. These are strong and thick and lie beneath the 
superior articular surface, on either side. They coalesce 
with the sides of the body and the root of the odontoid. 

Notches. The superior notches are very shallow and lie be- 
hind the superior articular surfaces. 

The inferior notches are very deep and lie in front 
of the inferior articular surfaces. 

LAMINAE. These are very thick and strong in the axis. 

SPINAL FORAMEN. This opening is smaller than that of the 
atlas, but it is still very large. 

SPINOUS PROCESS. This process of the axis is bifid, thick, 
and deeply grooved upon their inferior surface. 

TRANSVERSE PROCESSES. These processes of the axis are 
small and pointed. The foramen, at their bases, inclines 
obliquely upivards and outwards. 



88 SKELETON OF THE TRUNK 



THE 7TH CERVICAL VERTEBRA OR VERTEBRA 

PROMINENS. 

The spinous process of this vertebra is very thick, long, and 
prominent, from its horizontal position. It ends in a 
single tubercle for the attachment of ligamentum nuchae. 

The transverse processes are large, but slightly grooved, and 
seldom bifid. 

Its foramen is small or it may be absent. 

1ST DORSAL VERTEBRA. 

This vertebra presents a complete facet for the head of the 1st 
rib, and a demi-facet, below, for the upper facet of the 
head of the 2nd rib. 

Its articular process is slightly oblique in its axis, like the cer- 
vical vertebrae. 

9 th DORSAL VERTEBRA. 
This vertebra has only one demi-facet on the upper part of 
the body. 

ioth DORSAL VERTEBRA. 
This vertebra has but one facet on the upper portion of the 
body, and one on the transverse process. 

iith DORSAL VERTEBRA. 

This vertebra has only one facet. 

The transverse processes are short and have no articular facet 
for the ri ). 

12TH DORSAL VERTEBRA. 
This vertebra has but one facet for the rib, which is always 

complete. 
No facet for the rib exists on its transverse process. 
The inferior articular surfaces are convex and look forwards 

and outwards, like the lumbar vertebrae. 

5TH LUMBAR VERTEBRA. 

The body is markedly thicker in front than behind. 

The spinous process is small. 

The inferior articular processes are wider apart than the su- 
perior. 

The transverse processes are large, thick and are inclined 
slightly upwards. 



DEVELOPMENT OF VERTEBRAE. 89 

Structure of the Vertebrae. 

The structure of a vertebra differs in the different parts of 
the bone. The body is composed of light spongy cancellous tis- 
sue, having a thin coating of compact tissue on the surface, which 
is perforated by numerous orifices, some being of large size, for the 
passage of vessels. In the interior of the body are one or two 
large canals which converge either to one large aperture or to sev- 
eral smaller apertures upon its posterior surface. 

These canals serve for the reception of the veins which con- 
vey the blood from the bone. 

The arch of each vertebra and the processes projecting from it 
are covered by a thick layer of compact tissue. 

Development of the Vertebrae. 

A vertebra, as a rule, originally consists of three primary carti- 
laginous portions, one for each lamina and its subsequent processes, 
and one for the body. In the sixth week of foetal life, ossification 
commences in the laminae, and two weeks later, in the body. 

At 16 years of age three secondary centres of ossification ap- 
pear. One of these (occasionally two) is for the spinous process, 
and one for each transverse process. 

At about the 2\st year of age, two new secondary centres of 
ossification appear in the form of two plates, situated upon the 
upper and the lower surfaces of the bodies of the vertebrae. 

Thus' we have three primary and five secondary centres of ossi- 
fication in each of the vertebrae, and it is not until the 30th year 
of life that the entire skeleton of the vertebral column is thor- 
oughly ossified and all the component parts of each vertebra 
united. 

Exceptions to this general rule of development, however, may 
be found in the axis, atlas, vertebra prominens, and in the lumbar 
vertebrae. 

In the ATLAS, ossification commences, before birth, from two 
centres, located in the lateral masses, and progresses backwards 
rapidly into the posterior arch, while the anterior arch is entirely 
cartilaginous at the date of birth. By the 2nd or 3rd year the 
ossification of the posterior arch is completed, and the anterior 
arch is either gradually encroached upon or a special centre of 
ossification appears within it. 

In the ATLAS six centres of ossification arc required, before birth, 
for its development. Two of these are in the body of the odon- 
toid process, one is for the body of the bone, one for each of the 
lateral masses, and one for the apex of the odontoid process. 



9 o 



SKELETON OF THE TRUNK. 



The 7TH CERVICAL or VERTEBRA PROMINENS differs in its 
process of development from the other vertebrse, in that the ante- 
rior root of its transverse process is developed as a separate piece 
from the rest of the bone, thus requiring one additional centre of 
ossification. In rare instances, this portion continues to develope 
separately, and becoming lengthened, constitutes the so-called 
" cervical rib." 

The LUMBAR VERTEBRAE have two additionl centres of ossifica- 
tion (besides those peculiar to the vertebrae in general) for the tu- 
bercles which project from the back part of the superior articular 
surfaces. In rare cases, the transverse process of the lumbar ver- 
tebra may develope as a distinct and separate piece unconnected 
with the body, thus constituting the so-called " lumbar rib." 

VERTEBRAL COLUMN AS A WHOLE. 

The spinal column as a whole (including the sacrum and the 
coccyx), when viewed in front, resembles two pyramids united 
by their respective bases at a point which corresponds with the 
junction of the sacrum with the last lumbra vertebra. 

The upper pyramid when viewed more closely may be again 
compared to the union of three smaller pyramids, the first having 
its apex directed upwards and including the six lower cervical 
vertebrce, the second including the first four dorsal vertebrce and 
diminishing in size from above downwards, while the third extends 
from the fourth dorsal vertebra to the sacrum and presents a 
uniform increase in size as you approach the pelvis. 

If viewed laterally, the spinal column presents several curves 
which correspond with certain anatomical regions of the body and 
which are named the cervical, dorsal, lumbar and pelvic curves of 
the spine. 

These curves have their exact boundaries, as follows : 

_,. . 7 , ( Origin. From the apex of the odontoid process of 

The cervical curve (convex an- ) fa f, • r 

teiioriy.) ^ Termination. At the middle of 2d dorsal vertebra. 

„, , , , ( Origin. From the middle of the 2d dorsal vertebra. 

The dorsal curve (concave ante- j Tei ^ ination> At the middle of the I2th dorsal ver . 

rlorl y-) I tebra. 

The lumbar curve (convex an- j Origin. From the middle of the 12th dorsal vertebra. 

teriorly.) ( Termination. At the sacro-vertebral angle. 

The pelvic curve (concave ante- j Origin. From the sacro-vertebral angle. 

riorly.) \ Termination. At the tip of the coccyx. 

It will thus be seen that the spinal column as a whole, if 
viewed laterally, resembles somewhat in its shape the letter S. 
These curves are produced partly by the shape of the bodies of 



VERTEBRAL COLUMN AS A WHOLE. 



91 



the vertebrae and partly by the inter-articular fibro-cartilages in- 
serted between the bodies of each of the vertebrae. 

In counting the vertebrae upon the living subject, friction 
along the spinous processes will render them prominent. 

The spines of the third, fourth, and fifth cervical vertebrae can- 
not easily be felt, since they recede from the perpendicular line, in 
order to allow of free extension of the neck. 

In the cervical region the spinal opening is broad and triangu- 
lar in its shape. 
In the dorsal region the spinal opening is small and circular 

in its shape. 
In the lumbar region the spinal opening is triangular in shape 

and intermediate in its size. 
Within the cavity of the sacrum, the spinal opening is large 
and triangular above, small and flattened in the middle of the 
bone, and, below, the posterior wall of the canal is often deficient. 
The spinal column, if considered as a whole, often exhibits a 
slight lateral curvature, whose convexity is directed towards the 
right side of the trunk. This is probably the result, however, of 
excessive use of the right arm in preference to the left, since an 
opposite curvature has been occasionally noticed in persons who 
have habitually used the left hand in preference. 

On a lateral view of the spinal column we notice, in addition 
to the curves previously mentioned, the following points : 

(1.) The antero-posterior diameters of the bodies of the true 
vertebrce increase steadily, from above downwards, till 
the last lumbar vertebra is reached. 
(2.) The pedicles of the cervical region are concealed. 
(3.) The intervertebral foramina increase in size, from above 
downwards. 
(4.) The intervertebral foramina change their relation to the 
transverse processes, since, in the cervical region, they 
lie between the transverse processes, while, in the dorsal 
and lumbar regions, they lie in front of those processes. 
(5.) The transverse processes change in their relation to the 
pedicles and the articular processes, as indicated in the 
table below. 

Relation of the Transverse Process of the Vertkhr r.. 



Transverse Process. 


Pedicle. 


Articular Process. 


In the cervical region. 
In the dorsal region. 
In the lumbar region. 


Outside of 

Behind 

Behind 


In front of 
Behind 
In front o( 



9 2 



SKELETON OF THE TRUNK. 



(6.) The transverse processes of the dorsal region, on account 
of their inclination backwards, describe a greater curve 
tllan the bodies of that region. 
(7.) The spinous processes of the dorsal region, on account of 
their inclination downwards, describe a lesser curve 
than do the bodies of the vertebrae of that region. 
On viewing the spinal column posteriorly, we notice the fol- 
lowing points of difference in the cervical, dorsal and lumbar 
regions : 

C Broad and shallow in the cervical region. 
(i.) The vertebral groove is < Narrow and deep in the dorsal region. 

( Narrow and shallow in the lumbar region. 

(2.) The lamina are not equidistant from each other in all 
parts of the spinal column, being widest apart in the 
lumbar region and nearest together in the middle of 
the dorsal region. 
(3.) The width between the tips of the transverse processes of 
the vertebrae also varies greatly. It increases, from 
above downwards, in the cervical region, diminishes in 
the dorsal region, and again increases in the lumbar 
region, till it reaches its maximum at the base of the 
sacrum. 
The superior articular facets of the spinal column look up- 
wards in the cervical region, outwards in the dorsal region, and 
inwards in the lumbar region. It will thus be seen that the cer- 
vical vertebrae can be most easily dislocated. 

This important point can be easily remembered by writing 
the three last vowels, I, O. U., and over them the initial letters 
of the regions of the spine, in their order from below upwards, thus 
indicating the direction of the facet in each region. 



I. 



C. = Lumbar. 
U. = Inwards 



Dorsal. 
Outwards. 



Cervical. 
Upwards. 



The length of the true spinal column i. e. above the sacrum, 
is usually one-third of the height of a perfectly proportioned man. 

Each vertebra has three primary centres of ossification, and 
five complimentary centres. 

The three primary centres of ossification are as follows : \ ^ or } e ,° X 

3 
f For upper surface. . . . 1 

The five complimentary centres are as follows : iZ or ! ower surface \ 

* s I Jbor trans, processes,. . 2 

^ For spinous process. . . I 



THE THORAX. 93 

Important Anatomical Relations of Special Vertebrae. 

(1) The superior opening of the larynx. 

(2) The bifurcation of the common 

carotid artery. 
The 3rd Cervical Vertebra corresponds to (3) The point of origin of the external 

and internal carotid arteries. 
(4) The upper cervical ganglion of the 
sympathetic system of nerves. 

(1) The lower end of the larynx. 

(2) The upper end of the trachea. 
The 5th Cervical Vertebra corresponds to (3) The lower end of the pharynx. 

(4) The origin of the oesophagus. 

(5) The middle cervical ganglion of the 

sympathetic system of nerves. 

(i) The termination of the duodenum. 

(2) The commencement of the jejunum, 

(3) The lower border of the pancreas. 

(4) The upper root of the mesentery. 

(5) The origin of the superior mesen- 

teric artery. 

(6) The commencement of the thoracic 
The 2nd Lumbar Vertebra corresponds to duct. 

(7) The opening of the ductus com- 

munis choledochus. 

(8) The commencement of the vena 

portae. 

(9) The termination of the spinal cord. 

(10) The commencement of the cauda 

equina. 

(11) The crura of the diaphragm 

THE THORAX. 

The thorax is composed of 37 bones and 24 cartilages. Of 
these 37 bones 12 have already been considered as the dorsal ver- 
tebra, leaving the 24 ribs and the sternum to complete the unde- 
scribed bony portion of the thorax. 

THE RIBS. 

The ribs, twelve in number on each side, are osseous arches, 
extending from the vertebral column to the sternum. Their pos- 
terior four-fifths consists of bone and constitutes the rib, properly 
so called, while the anterior fifth is cartilaginous, and is called the 
costal cartilage. The term " rib " is used as a substantive ; when 
we have an adjective we are obliged to resort to the latin name. 

The ribs are named in numerical order, from above downwards, 
without regard to the character of the rib. In this respect the 
principle of the nomenclature of the ribs differs from that of the 
vertebral column. The ribs arise from cither side of the bodies 
of the dorsal vertebrae and unite, in front, with the exception o\ 
the last two ribs, with the sternum, either directly by its own car- 
tilage or indirectly through the intervention of the common cos- 
tal cartilages. 



94 SKELETON OF THE TRUNK. 

The ribs are of three kinds and are named as follows : 

1st. True Ribs (7 in number), which articulate with the 

sternum by their own cartilages. 
2nd. False Ribs (3 in number), which have a common cartilage 

which does not reach the sternum. 
3rd. Floating Ribs (2 in number), which are movable, at their 

anterior extremity, in the walls of the abdomen. 
The ribs increase in their length, from above downwards, from 
the first to the seventh, when the maximum length is 
attained. The lower four decrease in length from the 
eighth to the last. 
The breadth of the ribs increases steadily from the first to the 
last, as does also the width of the intercostal spaces. 

The obliquity of the ribs increases from the first to the ninth, 
and decreases from the ninth to the twelfth rib. 

The ribs are both curved and twisted upon themselves, this 
curve being most marked in the vicinity of the posterior angle of 
the bone. 

The angle of the ribs is farther from the head of the bone, as 
you descend from above downwards. 

The rib is the most vascular bone, in proportion to its size, in 
the human body. 

The vessels of the rib run near to its lower border, and, in tap- 
ping the chest, the trochar should be inserted as near to the up- 
per border of the rib as possible in order to avoid haemorrhage 
from injury to these vessels. 

The spines of the dorsal vertebrae, on account of their obliquity, 
do not lie on a level with the heads of the ribs which correspond 
to their bodies, but nearly with the level of the rib next below. 
This rule, however, does not apply to the eleventh and twelfth 
vertebrae. This point is of value in judging of the situation of 
the individual ribs, on the posterior surface of the thorax. 

Each rib presents for anatomical examination a shaft and two 
extremities. The posterior extremity presents a head, a neck and 
a tubercle. 

The following points of interest pertaining to these particular 
localities will be found embodied in the description given below. 

(1.) Posterior Extremity. 

Head of Rib. 

(1.) This portion of the bone presents two oblique facets, 
which are for the purpose of articulation with the 
bodies of two adjoining vertebrae. 



THE RIBS. 95 

(2.) A horizontal ridge exists between these facets, to 
which the interarticular ligament is attached. 
Neck of Rib. 

(1.) The neck is one inch in length and is flattened from 
before backwards. 

(2.) Its anterior surface is smooth. 

(3.) Its posterior surface is roughened for the costo- 
transverse ligments. 

(4.) Its upper border has a crest, for the superior costo- 
transverse ligments. 

(5.) Its lower border is rounded and smooth. 
Tuberosity of Rib. 

(1.) This prominence is most markedly developed upon 
the upper ribs. 

(2.) Its articular portion is revealed by a facet, into which 
the extremity of the transverse process of the in- 
ferior vertebra, with which the rib is connected, is 
adapted. 

(3.) Its 7ion-articular portion is roughened for the attach- 
ment of the costo-transverse ligament. 

(2.) The Shaft. 

Exterior Surface. 

This is convex in its form and exhibits three points 
of interest, the posterior and anterior angles, and 
a posterior rounded portion. 
(1.) The posterior angle consists of a rough line running 
downwards, which gives attachment to the follow- 
ing muscles : 

The tendons of the sacro-lumbalis. 
The accessorius. 
The cervicalis ascendens. 
(2.) The anterior angle, which is similar to the posterior 

but less strongly marked. 
(3.) A rounded portion, which lies between the tubercle 
and the angle of the rib, for the attachment of the 
fibres of the longissimus dorsi muscle. 
Interior Surface. 

This surface is concave in form, and from the twisted 
condition of the ribs, looks upwards, at the back 
portion of the thorax, and downwards, in the an- 
terior portion of the chest. 
It presents a ridge, which is most marked in the 



9 6 SKELETON OF THE TRUNK. 

posterior two-thirds of the shaft of the rib, and 
which gives attachment to the internal intercostal 
muscles. This ridge forms the internal boundary 
of a groove along the lower border of the rib for 
the protection of the intercostal vessels and nerves. 
Upper Border. 

This portion of the shaft of the rib is smooth and 
gives attachment to both the external and internal 
intercostal muscles. 
Lower Border. 

This border is thin and sharp and helps to form the 
groove for the intercostal vessels. It gives attach- 
ment to the external intercostal muscles. 

(3.) Anterior Extremity. 

This portion of the rib is compressed and flattened 
from before backwards. It is studded with minute 
foramina for the passage of vessels, and presents 
for inspection a deep oval pit or depression, into 
which the corresponding costal cartilage is in- 
serted. 

PECULIAR RIBS. 

The 1st, 2nd, 10th, nth and 12th ribs present certain pecu- 
liarities which enables the accomplished anatomist to readily dis- 
tinguish them, even if detached from the skeleton. These points 
of peculiarity will be found enumerated below in detail. 
First Rib. 

f £'} t r f u i h i m P re ^oniox thescalenus medius muscle. 
T , ,, , ( 2 -) A tubercle for the scalenus anticus muscle 

The upper surface presents I (3.) Two grooves, the anterior one bein™ for the subcla 

vian vein, and the posterior one for the subclavian 

(__ artery. 

The under surface has neither a ridge nor a groove. 
The inner border presents apart of the tubercle for the scalenus 
anticus muscle. 

The /lead has only a single facet for articulation with the 1st 
dorsal vertebra. 

The tuberosity and the angle are blended together. 
The anterior extremity is unusually large and thick. 
Second Rib. 

({1.) Rough spots near its middle for the 1st and 
The outer ox upper surface presents^ ? nd serratlon * of the serratus ma^nus muscle. 

1 (2.) A rough posterior impression for the scalenus 
L posticus muscle. 



COSTAL CARTILAGES. gy 

The inner or under surface presents a short and slight groove. 

The tubercle and the angle are close together. 
Tenth Rib. 

The head of this rib has only a single articular facet. 
Eleventh Rib. 

This rib has no neck, no tuberosity and but a single articular 
facet upon its head. 
Twelfth Rib. 

This rib has no neck, no angle, no tuberosity, no groove. 

Its head has but a single articular facet. 

Costal Cartilages. 

The costal cartilages (from costa — a keeper — because they are 
the guardians of the organs of the chest) compose about one- 
fifth of the entire circumference of the chest, the ribs, sternum 
and the vertebrae forming the remaining four-fifths of the circum- 
ference. They are 12 in number on each side and are arranged as 
•follows : 

The first seven connect the corresponding true ribs to the 
sternum. 

The next three do not connect with the sternum but are joined 
to the cartilage of the rib next above. 

The last two are not attached in front. 

The costal cartilages decrease in breadth from the first to the 
last as do the spaces between the ribs. 

They increase in length from the first to the seventh costal car- 
tilage and they diminish from the eighth to the twelfth. 

The direction of the costal cartilages also varies in the different 
portions of the thorax. The first cartilage is directed obliquely 
downwards, the second cartilage lies horizontally, the third is di- 
rected slightly upwards, the last two cartilages follow the direc- 
tion of the ribs to which they are attached, while all the remaining 
cartilages follow the direction of the ribs for a short distance and 
then ascend more and more obliquely either to join the sternum 
or the costal cartilage next above it. 

The costal cartilages all taper tozvards their sternal end except- 
ing the first and the second. 

The sixth, seventh, eighth and the ninth are enlarged at their 
points of articulation with each other. 

The costal cartilages present the following parts of interest : 

(1.) Anterior surfaces. 

These are convex in shape, and looks upwards and for- 
wards. 



gS SKELETON OF THE TRUNK. 

They give attachment to the following two muscles : 
the subclavius and the pectoralis major ; and also 
to the rhomboid or costo-clavicular ligament. 
(2.) Posterior surfaces. 

These are concave in shape and look downwards and 

backwards. 
They give attachment to three muscles : the triangu- 
laris sterni, the transversalis abdominis and the dia- 
phragm.) 
(3.) Upper borders. 

These are concave and serve for the purpose of attach- 
ment of the intercostal muscles. 
The 7th, 8th and 9th cartilages reveal a depression or 
facet, for articulation with the adjoining cartilage. 
(4.) Lower borders. 

These are convex and serve for the purpose of attach- 
ment of the intercostal muscles, the internal oblique 
muscle of the abdomen, and the rectus abdominis. 
The 6th, 7th and 8th cartilages present, upon this 
border, articular facets for the other cartilages named 
above. 
(5.) Costal extremities. 

The costal cartilages are largest where they join the 
rib. This extremity is rough and rounded and is im- 
planted into and becomes continuous with the anterior 
extremity, of its corresponding rib. 
(6.) Anterior or Sternal extremities. 

This extremity is smaller than that attached to the 
ribs. It is smooth and triangular in shape and fits 
into an articular notch in the sternum, in the 2nd, 3rd. 
4th, 5th, 6th and 7th cartilages. In the 8th, 9th and 
10th cartilages this extremity joins with other cartil- 
ages. In the nth and 12 cartilages this extremity is 
free, while in the 1st costal cartilage it appears as a 
direct continuation of the sternum itself. 

THE STERNUM. 



The sternum presents for examination the following parts 

The Manubrium. 
3 separate pieces called -j The Gladiolus. 

The Ensiform or Xiphoid Appendix. 



Originally the sternum consists of six points of ossification, of 



2 Borders. 
2 Surfaces. 



THE STERNUM. 99 

which the four middle ones are joined together before adult life, 
while the upper and the lower points remain as distinct and sep- 
arate portions, till age becomes somewhat advanced. 

The various portions of the sternum, mentioned above, present 
the following points of interest. 

Manubrium (the handle). 

This is the thickest part of the sternum. It forms the upper 
portion of the bone and is broadest above, and narrowest where 
it joins the gladiolus. It articulates with the sternal end of the 
clavicle and the first costal cartilage and unites, in part, with the 
second costal cartilage. 

Gladiolus (the sword). 

This portion of the sternum is situated in the central portion 
of the bone. It is long and blade-like in shape (from which it 
derives its name) and is broadest a little below its centre. It 
unites with the third, fourth, fifth and sixth costal cartilages, and, 
in part, with the second and with the seventh. 

It is sometimes perforated by the sternal foramen. 

Ensiform or Xiphoid Appendix (tip of the sword). 

This terminal portion of the breast bone may be either broad, 
pointed, or forked in its shape. It is occasionally perforated and 
sometimes it is deflected towards one side. It articulates, in part 
only, with the seventh costal cartilage. It gives attachment to 
the following structures : 

(1) The linea alba. 

(2) The anterior abdominal aponeurosis. 

(3) The inner fibres of the rectus abdominis muscle. 

Anterior Surface. 

The anterior surface of the sternum varies in its configuration 
in the three segments forming that bone. In the manubrium, it 
is convex from side to side and concave from above downwards ; 
in the gladiolus it is flat and traversed by three horizontal lines 
which indicate the location of the original four segments, which 
subsequently united. In the xiphoid appendix, it is occasionally 
curved. 

It gives attachment to the following structures : 

(1) The sternal portion of the sterno-mastoid muscle. 

(2) The pectoralis major muscle. 

(3) The chondro-sternal ligaments. 

(4) The chondro-xiphoid ligaments. 



100 skeleton of the trunk. 

Posterior Surface. 

This surface of the sternum is smoother than the anterior, is 
slightly concave, and is marked, in the- region of the gladiolus, by 
the same three transverse lines seen upon its anterior surface, but 
which are much less distinct. It gives attachment to the follow- 
ing structures. 

(i) The sterno-hyoid muscle. 

(2) The sterno-thyroid muscle. 

(3) The triangularis-sterni muscle. 

(4) The median fasciculus of the diaphragm. 

(5) The posterior chondro-sternal ligaments. 

Superior Border. 

This portion of the sternum is of extreme thickness. It pre- 
sents, in its centre, a notch termed the interclavicular notch, and, 
on either side of this notch, two depressions termed the clavicular 
facets. These facets are for the articulation of the clavicle with 
the sternum. 

Lateral Borders. 

The lateral borders of the sternum present seven articular 
notches or depressions for the articulation of the costal cartilages 
of the ribs. Of these seven depressions, the manubrium has two, 
one high up and one just at its point of junction with the gladi- 
olus, and the gladiolus has five, the last one being at its point of 
junction with the ensiform appendix. 

Muscles. 

The sternum or breast-bone affords attachment to 9 pairs of 
muscles and to I single muscle, viz., the diaphragm. 

These muscles may be thus classified on a basis of the loca- 
tion of their point of attachment to the sterum. 

{Sternocleidomastoid. 
Sterno-hyoid. 
Sterno-thyroid. 
f Rectus abdominis. 
, . r ' , Obliquus abdominis externus 
To the lower portion of the bone \ ^ P. air5 i ° rau ? c es# 1 Obliquus abdominis internus 
* < 1 single muscle. ] Transversalis ABu0 minis. 

[ The Diaphragm (single). 

To the anterior surface of the bone 1 muscle \ Pectoralis Major. 

To the posterior surface of the bone I muscle \ Triangularis Sterni. 

Articulation. 

The sternum articulates with the two clavicles, and with the 
cartilages of the seven true ribs and the common cartilage of the 
three false ribs. 



the thorax in general. ioi 

Development. 

The sternum is developed by six centres of ossification, the 
situation of which is shown in the following table ; 

_,. „ • j i j u • ( For the manubrium one centre. 

The Sternum is developed by six cen- \ For thfi ladlolus four centres< 

tres of ossification, as follows : J For ^% miform a pp endix one cen tre. 

Two small additional centres, called the episternal centres, are 
described by some authors as existing upon either side of the in- 
terclavicular notch. 

THE THORAX IN GENERAL. 

The thorax is conical in its shape, with convex walls and with 
an axis which is directed obliquely downwards and forwards. It 
is broadest below and in its transverse measurement. It is 
bounded by the dorsal vertebrae, the ribs, the costal cartilages and 
the sternum. It presents for examination, 

An upper opening or apex, 

A lower opening or base, 

An outer surface, 

An internal cavity. 
Each of these portions deserve a special consideration, since 
a special description of the individual bones, still leaves unmen- 
tioned many points of practical interest and value. 

Upper Opening. 

The thoracic entrance is narrow, heart-shaped, and is inclined 
obliquely downwards and forwards. 

It is bounded, behind, by the first dorsal vertebra, laterally, by 
the first rib and its costal cartilage, and, in front, by the first bone 
of the sternum. It gives passage to the following structures : 
(i) The trachea. 

(2) The oesophagus. 

(3) The large vessels of the neck. 

(4) The pneumogastric nerves. 

(5) The phrenic nerves. 

(6) The sympathetic nerves. 

(7) The apex of the lung during inspiration. 

(8) The thoracic duct. 

Lower Opening. 

This opening of the thorax is widest, in its transverse diameter, 
opposite the level of the ensiform appendix. Its anterior diame- 
ter is encroached upon, by the prominence of the bod)- of the last 
dorsal vertebra. It is filled in below by the diaphragm, which 



102 SKELETON OF THE TRUNK. 

thus separates the cavity of the thorax from the cavity of the 
abdomen. 

It is bounded behind by the twelfth dorsal vertebra, laterally 
by the lower two ribs, by the anterior portions of the false ribs 
arid by the common costal cartilage, which unites the false ribs 
to the sternum, and, in front, by the ensiform appendix of the 
sternum. 

Outer Surface. 

The exterior aspect of the chest measures, in front, about 8 1 
inches in depth, while, in its posterior portion, the depth of the 
chest is about 12 inches, and, if the sides be measured along the 
convexity of the ribs, the lateral depth of the thorax is about 12 
inches. 

The posterior aspect of the thorax is depressed in the median 
line, and marked by the prominences of the spines of the vertebrae, 
by the two vertebral grooves on either side of the spines, by the 
transverse processes of the dorsal vertebrae and by the articulations 
between the ribs and the transverse processes. Away from the 
median line the posterior wall of the thorax becomes convex from 
the outward curve taken by the ribs after they leave their rela- 
tions with the dorsal vertebrae. 

Cavity. 

The cavity of the thorax is partly divided, in the median 
line, by the prominence of the bodies of the dorsal vertebrae, 
on each side of which the cavity of the chest is prolonged back- 
wards into two deep grooves or channels. The transverse diam- 
eter of the interior of the chest is greater than is its antero-posterior 
measurement. The cavity of the thorax contains the following 
structures : 

(1) The trachea, bronchial tubes and lungs. 

(2) The heart and pericardium. 

(3) The arch of the aorta, 

(4) The thoracic aorta and its branches. 

(5) The pulmonary artery, 

(6) The internal mammary artery. 

(7) The superior and inferior venae cavae. 

(8) The pulmonary veins. 

(9) The innominate veins. 
(10) The azygos veins, 
(n) The bronchial veins. 

(12) The oesophagus. 

(13) The thoracic duct. 



THE THORAX IN GENERAL. IO3 

(14) The pneumogastric nerves. 

(15) The phrenic nerves. 

(16) The splanchnic nerves. 

(17) Lymphatic vessels and glands. 

These parts will be found described under the respective 
heads to which they properly belong. 

The thorax of the female differs from that of the male in the 
following respects : 

1. It has a smaller general capacity than the male thorax. 

2. The sternum is shorter. 

3. The superior opening is larger in proportion to the lower. 

4. The upper ribs are more movable. 

This latter peculiarity is explained as a device of nature to af- 
ford easy respiration during the period of pregnancy. 

In fleshy persons, it is often difficult to count the ribs, and, as 
it is often necessary to definitely locate certain points upon the 
external surface of the chest, the following guides may prove of 
value ; 

1. The nipple of the male usually corresponds to the interval 
between the fourth and fifth ribs and is situated about three-quar- 
ters of an inch external to their cartilages. 

2. The scapula extends to the space between the seventh and 
the eighth ribs. 

3. The lower border of the pectoralis major muscle is nearly 
parallel with the fifth rib. 

4. A line drawn around the chest on the level of the nipple 
intersects the sixth, rib at the point midway between the sternum 
and the spinal column. As this is the seat of election in tapping 
the chest, this guide has a practical value. 

5. As the ribs incline downwards from their point of attach- 
ment to the transverse processes of the dorsal vertebrae, it is to be 
remembered that the level of a rib on the anterior aspect of the 
chest does not correspond to the level of the same dorsal verte- 
bra, and a guide may be afforded in estimating the approximate 
relation of any given point by remembering that the tip of the 
sternum is nearly on a level with the 10th dorsal vertebra. 

6. The junction of the first and the second bones of the ster- 
num corresponds to the anterior extremity of the 2nd rib, and 
this point can usually be detected by a transverse ridge upon the 
sternum. 

THE PELVIS. 

The remaining four bones, pertaining to the trunk, which 



104 SKELETON OF THE TRUNK. 

have not yet been considered, are those which enter into the for- 
mation of the pelvis. 

The pelvic bones may be divided in two mesial and one pair, 
as follows : 

*-» wTcoccvx: 

One pair (2) \ Ossa Innominata. 

• . Total, 4 

Each of these bones have points of great practical interest. 
They will be considered in the order of their enumeration. 

SACRUM. 

The sacrum or rump bone consists of five vertebrae blended 
together into one bone. In some cases the bones entering into 
the sacrum may be increased to six, and occasionally they may be 
diminished to four. 

The shape of the sacrum is that of a quadrangular pyramid 
with a truncated apex, which looks downwards, while the base is 
directed upwards. It is situated within the pelvis at its posterior 
portion, and in the line of direct continuation of the vertebral 
column. In the female sex, it is broader, less curved and more 
obliquely situated within the pelvis. The sacrum forms by its 
junction with the last lumbar vertebra, a projection into the cavity 
of the pelvis termed the promontory of the sacrum. 

This bone presents for examination the following portions : 

An anterior surface. 

A posterior surface. 

Two lateral surfaces. 

A base. 

An apex. 

A canal. 

Anterior Surface. 

This portion of the sacrum is concave both from above down- 
wards and also from side to side. It is traversed by four trans- 
verse ridges, which indicate the union of the five different pieces 
of which the bone was composed, and, at the ends of these ridges, 
are seen the four anterior sacral foramina, through which escape 
the terminal filaments of the cauda equina, to form the sacral 
plexus of nerves. Four broad shallow grooves are also present 
upon each side of this surface of the sacrum, into which the fibres 
of the pyriformis muscle are inserted, and three prominent ridges 
divide and separate these grooves, which also give attachment to 
slips of the same muscle. That part of the bone, where these 



THE SACRUM. 105 

ridges and grooves are present, is called the lateral mass of the 
sacrum, and results from the blending together of the anterior 
portion of the transverse processes and the bodies of the five 
pieces of the sacrum. 

Posterior Surface. 

This surface of the sacrum is narrow, convex and uneven. In 
the median line, as the surface of the bone is examined, there is 
perceived, (1) Three or four tubercles, -which represent the spinous 
processes of the blended vertebrae. (2) A longitudinal groove, on 
each side of the tubercles, which correspond to the articular pro- 
cesses of the vertebrae. (3) A series of indistinct tubercles, the 
lower two of which are blended together and form the sacral cor- 
nua, or horns of the sacrum, which articulate with similar cornua 
upon the coccyx. (4) Four posterior sacral foramina, which are 
smaller than those upon the anterior surface, and which transmit 
the posterior branches of the sacral nerves. The posterior sacral 
foramina are directly opposed to the anterior, and hence it is pos- 
sible for a pointed instrument to pass through both and wound 
the pelvic viscera, (5) A series of eminences, often called the pos- 
terior transverse processes of the sacrum, and which correspond to 
similar eminences upon the anterior surface. 

The space contained between these latter named eminences 
and those tubercles in the median line is called the sacral groove, 
which is continuous, above, with the vertebral groove, and which 
gives origin to the erector spinae muscle. 

Lateral Surfaces. 

The lateral surface of the sacrum is broad, above, and gradually 
becomes narrower and narrower, as the lower extremity of the 
bone is approached. The upper portion is termed the auricular 
surface, from its resemblance to the auricle or pinna of the ear. 
This portion is covered with cartilage, and serves the purpose of 
articulation with the ilium. 

Posterior to the auricular surface, are several deep and rough 
depressions for the insertion of the posterior sacro-iliac ligaments. 
As the lateral surface becomes narrowed, a thin border is perceived, 
which affords attachment for the sacro-sciatic ligaments and. for 
a few fibres of the gluteus maximus muscle, and which terminates 
in the inferior lateral angle of the sacrum. Below this angle is 
perceived a deep notch, which is occasionally transformed into a 
foramen by the articulation of the transverse process of the 
coccyx with the sacrum. This foramen gives passage to the 5th 
sacral nerve. 



106 skeleton of the trunk. 

Base of Sacrum. 

This portion of the sacrum has the appearance of a lumbar 
vertebra. Thus the body, pedicles, laminae, spinous and trans- 
verse processes, etc., belonging to the 1st sacral vertebra may be 
discerned. The spinal foramen is large and triangular, the artic- 
ular processes are similar to those of the lumbar vertebrae, but 
more widely expanded, while the body is prominent and forms 
a part of the sacro-vertebral angle. 

Apex of Sacrum. 

The apex of the sacrum curves downwards and forwards, and 
presents a small oval surface, articulating with the first bone of 
the coccyx. 

Sacral Canal. 

The sacral canal is large and triangular in shape, at the upper 
portion of the bone, but it becomes small in size and flattened, at 
the lower portion. In this latter situation the posterior wall is 
incomplete, from the non development of the laminae and the 
spinous processes, hence the serious effects of injuries to this part. 
Sloughs from bed-sores, in this region sometimes open into the 
spinal canal. 

Into it open, laterally, both the anterior and posterior sacral 
foramina. 

These foramina, as well as the sacral canal, transmit only 
branches of the cauda equina, since the spinal cord itself extends 
only to the 2nd lumbar vertebra. 

Development of the Sacrum. 

The sacrum is developed by 35 centres of ossification, since it 

consists of 5 vertebrae. These centres are arranged as follows : 
The bodies of the 5 vertebrae have each 3 centres. Total, 15 
The arches of each vertebra have 2 centres. " 10 

The lateral masses of the sacrum have each 3 centres. " 6 
The lateral surfaces of the sacrum have each 2 centres. " 4 

Total, 35 
Muscles of the Sacrum. 

The sacrum affords attachment to eight pairs of muscles, as 
follows : 

To its anterior surface i muscle \ Pyriformis. 

To its base I muscle^ Iliacus. 

To its side I muscle <( Coccygeus. 

f Latissimus Dorsi. 
I Erector Spin^e. 
. To its posterior surface 5 muscles ^j Multifidus Spin/e. 

Gluteus Maxim us, 
[Extensor Coccygis. 



The Sacrum affords attach- 
ment to 8 muscles, as fol- 
lows : 



THE COCCYX. 



107 



Articulation. 

The sacrum articulates with two mesial bones (the 5th lumbar 
vertebra and the coccyx), and with one pair of bones (the ossa 
innominata), making a total of 4 bones. 

THE COCCYX. 

The coccyx or huckle bone, so called from its resemblance to 
a cuckoo's beak, consists of four and sometimes of five bones, 
which are incomplete and rudimentary vertebrae. These vertebrae 
are incomplete, since they are deficient in pedicles, laminae, and in 
spinous processes, as well as in a spinal canal and intervertebral 
foramina. They are also rudimentary, since the transverse and 
articular process are distinguishable in the first two, while the 
others are reduced to mere nodules of bone. 

The first segment of the coccyx occasionally exists as a sepa- 
rate piece and is by far the largest of the five segments. Its 
superior articular process is sometimes prolonged into comua, 
which articulate with the sacrum and help to form a foramen for 
the 5th sacral nerve. 

The gradual diminution in the size of the pieces gives to the 
coccyx a triangular form, the base of which corresponds to the 
sacrum. 

The borders of the coccyx are narrow and give attachment, 
upon either side, to the sacro-sciatic ligaments and the coccygeus 
muscle. 

The apex of the coccyx is rounded and gives attachment to 
the tendon of the external sphincter ani muscle. Occasionally the 
apex of the coccyx is bifid and it may be deflected to one side. 

Muscles of the Coccyx. 

The coccyx affords attachment to 5 pairs of muscles, which 
may be thus classified : 

\ To the posterior surface, 2 \ ^teiis Maximus. 
The Coccyx affords attachment * J { Extensor Coccygis. 

to 5 muscles, as follows :....] To the anterior surface, I \ Levator Ani. 

To the margin or side, I \ Coccygeus. 
To the apex or tip, 1 \ SPHINCTER Ani. 

Centres of Ossification. 

The coccyx is developed by four centres of ossification, one 
for each piece of the bone. 

Articulations. 

The coccyx articulates with one bone, viss^ the sacrum. 



108 SKELETON OF THE TRUNK. 

OS INNOMINATUM. 

The os innominatum (bone without a name) or coxal bone is 
formed by the union of three distinct bones, each of which has 
two names, as follows : 

(i) The Ilium or Haunch bone. 

(2) " Ischium or Seat bone. 

(3) " Pubes or Share bone. 

It is a large, irregular, flat bone, constricted towards its mid- 
dle portion and expanded above and below. It is also so twisted 
upon itself, that its superior expanded portion is directed inwards, 
at its posterior part, and outwards at its anterior part, while its 
inferior portion is curved inwards, anteriorly, as far as the median 
line of the body. The three portions of which it is composed, 
remain distinct until about the 14th year of age, when they be- 
come united as one bone. 

These three portions, the ilium, the ischium and the pubes 
will be considered therefore separately, after first describing two 
important portions of the bone which do not properly pertain to 
either of the three divisions alone. These two important portions 
are, (1) The acetabulum or cotyloid cavity, and (2) The obturator 
or thyroid foramen, or foramen ovale. 

ACETABULUM OR COTYLOID CAVITY. 

This cavity serves the purpose of affording an articular sur- 
face for the head of the femur. It is deep, hemispherical in 
shape and is composed of three parts. Of these three parts, the 
ilium forms a little less than two-fifths, including, however, the 
largest portion of the articular ring ; the ischium forms a little 
more than two-fifths of the whole cavity, including the largest 
proportion of its central depressed portion ; the pubes form the 
balance of the acetabulum or about one-fifth of the whole. 

The direction of the cavity of the acetabulum is downwards, 
forwards and outwards. 

It is surrounded, for the greater part of its circumference, by a 
ring or elevated margin of bone for the attachment of the cotyloid 
ligament, which deepens the cavity. This ring is deficient, how- 
ever, in front and below, and is most extensively developed at its 
posterior portion. 

The cotyloid notch is an opening, in margin of the acetabulum, 
leading into its central depressed portion, which transmits the 
nutrient vessels to the joint and which is continuous with the 
central depressed portion. 



THE OS INNOMINA TUM. 



IO9 



The margins of this notch give attachment to the round and 
the transverse ligaments of the hip joint. 

The central depression of the acetabulum lodges a mass of fat 
as a bed for the round ligament of the hip joint. It is nearly 
circular in shape, is rough upon its surface, and is continuous 
with the cotyloid notch. It is formed chiefly by the ischium. 

OBTURATOR OR THYROID FORAMEN. 

This foramen is comprised between the pubes and the ischium. 
It is large and oval in the male sex, and smaller and triangular in 
the female. 

It is closed by a membrane, called the obturator membrane, 
except at its upper part, where this membrane converts a groove, 
situated upon the under surface of the horizontal ramus of the 
pubes, into a complete foramen for the passage of the obturator 
vessels and nerves. 

THE ILIUM. 

The ilium is the superior expanded portion of the os innomi- 
natum. Its chief points of special anatomical interest can best be 
presented by a separate description of the following portions of 
the bone. 

(1) The outer surface, or dorsum. 

(2) The inner surface. 

(3) The upper border, or crest. 

(4) The anterior border. 

(5) The posterior border. 

Outer Surface or Dorsum. 

This portion of the ilium is convex in front, where it looks 
downwards and outwards, while, behind, it is concave and looks 
downwards, outwards and backwards. 

(1) Three curved lines. 

(2) Three surfaces for muscular at- 
It presents for examination the following points tachment. 

of interest : (3) A section of the acetabulum. 

(4) A groove for the reflected tendon 
of the rectus femoris. 

The three curved lines, mentioned above, are termed respect- 
ively the superior, the middle, and the inferior curved lines of the. 
dorsum ilii. They commence at different points upon this sur- 
face of the bone and all terminate in the vicinity of the great 
sciatic notch. 

The superior curved line arises about two inches in front o( 
the posterior extremity of the crest, the middle curved line arises 



1 10 SKELETON OF THE TRUNK. 

one inch and a half behind the anterior extremity of the crest, 
and the inferior curved line arises at the anterior inferior spinous 
process of the ilium. 

The three surf aces for the attachment of muscles lie above and 
between the three curved lines of the dorsum ilii. From them 
arise the gluteus maxinus, the gluteus medius and the gluteus 
minimus muscles. 

The dorsum of the ilium presents also, (i) a triangular segment 
of the acetabulum (comprising about f of the whole cavity), (2) 
the upper portion of the rim of the acetabulum, and (3) a groove 
(sometimes a ridge) from which arises the reflected tendon of the 
rectus muscle. 

Inner Surface. 

This surface of the ilium presents the following parts : 

(1) The internal fossa or venter of the ilium. 

This is bounded below by the linea ileo-pectinea and 
presents, at its inferior part, a nutrient foramen. 

(2) The sacro-iliac surface. 

This portion of the bone is for articulation with the 
sacrum. It is covered with cartilage, and gives attach- 
ment to the posterior sacro-iliac ligaments. 

(3) A portion of the inner surface of the true pelvis. 

This portion of the ilium corresponds to the segment 
of the acetabulum previously described. 

Upper Border or Crest. 

This portion of the ilium is convex from before backwards, is 
curved into a segment of a circle, and, at its posterior portion, is 
concave from side to side, and, in its anterior portion, it is convex 
from side to side. It is thickest behind and in front, and thinnest 
at the sides of the ilium. It is divided into three lips, an outer 
lip, an interspace.called the interstice or middle lip, and an inner lip. 

To the outer lip are attached three muscles, viz., the latissimus 
dorsi, the obliquus abdominis externus, the tensor vaginae femoris, 
and the fascia lata of the thigh. 

To the inner lip are attached three muscles, viz., the transver- 
salis abdominis, the quadratus lumborum, and the erector spinae. 

To the middle lip is attached the obliquus abdominis internus. 

Anterior Border. 

This portion of the ilium is long, concave in form and nearly 
vertical in direction. It presents, as the border is examined from 
above downwards, the following points : 



THE ISCHIUM. HI 

(i) The anterior superior spinous process. 

This portion of the ilium gives attachment to three 
muscles and one ligament. The muscles are the sar- 
torius, the iliacus, and the tensor vaginae femoris. 
The ligament is called Poupart's ligament. 

(2) A notch, for the lower fibres of the sartorius muscle and 

for the external cutaneous nerve. 

(3) The anterior inferior spinous process. 

This gives attachment to the straight tendon of the 
rectus muscle. 

(4) A broad, shallow groove, for the passage of the psoas magnus 

and the iliacus muscles, from the cavity of the pelvis. 

Posterior Border. 

This portion of the ilium is shorter and more horizontal than 
the anterior border. It presents for examination the following 
points : 

(1) The posterior superior spinous process, for the erector spinae 

muscle and for the oblique sacro-iliac ligament. 

(2) The posterior inferior spinous process, for part of the great 

sacro-sciatic ligament. 

(3) The upper border of the great sacro-sciatic notch. 

THE ISCHIUM. 
The ischium is the lower, posterior and thickest portion of the 
os innominatum. It bounds the obturator foramen behind and in 
its lower portion, and presents for examination the following com- 
ponent parts : 

(1) The body of the ischium. 

(2) " tuberosity of the ischium. 

(3) " ascending ramus of the ischium 

Body of Ischium. 

This portion of the bone possesses three surfaces ; called re- 
spectively the exterior, interior and posterior surfaces, and three 
borders called the anterior, the outer and the inner borders. 

The exterior surface embraces a little more than two-fifths of 
the acetabulum, including the lower part of its rim, a portion of 
the colytoid notch, and the greater portion of its central depres- 
sion. It also exhibits a deep groove along its length, for the pas- 
sage of the tendon of the obturator externus muscle, and it as- 
sists in forming the posterior part of the circumference of the ob- 
turator foramen, from which portion arise the obturator externus 
and the adductor magnus muscles. 



112 SKELETON OF THE TRUNK. 

The interior surface forms the lower part of the lateral boundary 
of the true pelvis and the posterior portion of the circumference 
of the obturator foramen. It gives attachment to the obturator 
internus muscle and presents for examination two or three large 
foramina for vessels, and a groove for the passage of the pudic 
vessels and the pudic nerve. 

The posterior surface is quadrilateral in shape, is smooth upon 
its surface and is broader above than below. It gives attachment 
to four muscles, viz., the pyriformis, obturator internus and the 
two gemelli. 

The anterior border of the ischium is very thin and affords at- 
tachment for the obturator membrane. 

The outer border is thick and short. 

The inner border is long, and exhibits the following points of 
interest : 

(i) The lower portion of the great sacro-sciatic notch. 

(2) The spine of the ischium. 

(3) The lesser sacro-sciatic notch. 

The greater and lesser sacro-sciatic notches are converted into 
complete foramina by the sacro-sciatic ligaments and give passage 
to important structures, as follows : 

f (1) The Gluteal vessels. 

(2) The Superior gluteal nerve. 

(3) The Pyriformis muscle. 

(4) The Pudic vessels and nerve. 

(5) The Sciatic vessels and nerves. 

(6) The nerve to the Obturator internus mus- 
cle. 

(1) The Obturator internus muscle. 
The lesser sacro-sciatic notch transmits \ (2) The Pudic vessels (re-entering). 



The great sacro-sciatic notch transmits - 



(3) The Pudic nerve (re-entering). 

The spine of the ischium affords attachment to, (1) the lesser 
sacro-sciatic ligament, (2) to the following three muscles, viz., the 
gemellus superior, coccygeus and the posterior fibres of the 
levator ani. 

Tuberosity of the Ischium. - 

This prominent portion of bone is situated upon the lower 
and back part of the body of the ischium. It presents for consid- 
eration, (1) an outer lip, (2) an inner lip, and (3) four roughened 
spaces between the two lips. 

The outer lip affords attachment to three muscles, viz., the gem- 
ellus inferior, the quadratus femoris and the adductor magnus. 

The inner lip affords attachment to two muscles, viz., the 
transversus perinei and the erector penis or clitoridis, and also to 



THE TUBES. 



113 



the cms penis or clitoridis and to the falciform expansion of the 
great sacro-sciatic ligament. 

The four rough spaces, between the two lips, give attachment 
to the adductor magnus, the semimembranosus, the common ten- 
don of the semitendinosus and the biceps, and to the great sacro- 
sciatic ligament. They are denominated the two superior and the 
two inferior spaces. 

Ascending Ramus of the Ischium. 

This portion of the bone is thin and flattened. Its direction 
is upwards and it bounds the obturator foramen inferiorly. It 
joins with the descending ramus of the pubes and presents for 
examination, (1) an outer surface, (2) an inner surface, (3) an upper 
border, and (4) a lower border. 

The outer surface is rough and gives attachment to three 
muscles, viz., the gracilis, the obturator externus and the adductor 
magnus. 

The inner surface is smoother than the outer and affords at- 
tachment for the obturator internus muscle. 

The upper border is thin and sharp and serves as a point of 
attachment for the obturator membrane. 

The lower border is rough and thick and gives attachment to 
three muscles (the gracilis, the erector penis or clitoridis and 
transversus perinei) and also to the crus penis or clitoridis, the 
deep perineal fascia and the deep layer of the superficial perineal 
fascia. 

THE PUBES. 

This bone forms the anterior and inner portion of the os inno- 
minatum. It bounds the obturator foramen above and in front 
and may be subdivided for convenience of description into 

(1) A body. 

(2) A horizontal ramus. 

(3) A descending ramus. 

The body of the Pubes. 

This portion of the bone is quadrilateral in its shape and is 
flattened, from before backwards and outwards. It presents for 
consideration the following portions: (1) An anterior surface, (2) 
a posterior surface, (3) an upper border, (4) an inner border, and 
(5) an outer border. 

The anterior surface is rough and slightly excavated. It gives 
attachment, from above downwards, to five muscles, as follows : 
The adductor longus, the obturator externus, the adductor brevis, 
the abductor magnus, and the upper portion of the gracilis. 



114 SKELETON OF THE TRUNK. 

The posterior surface is smooth and concave from side to side. 
It gives attachment to two muscles, viz. : the obturator internus, 
and the levator ani, and it also affords insertion for the pubo- 
prostatic ligaments, and for the anterior true ligaments of the 
bladder. 

The upper border of the body of the pubes presents four points 
of especial interest and value. These are the angle, the crest, 
and the spine of the pubes, and the commencement of the ilio- 
pectineal line. 

The angle of the pubes corresponds to the points of decussa- 
tion of the internal pillars of the external abdominal rings. 

The crest of the pubes affords attachment, posteriorly, to the 
conjoined tendon of the external oblique and transversalis mus- 
cles, and, anteriorly, to the rectus abdominis and pyramidalis 
muscles. 

The spine of the pubes affords attachment to Poupart's liga- 
ment and the external pillar of the abdominal ring. 

The linea ilio-pectinea affords attachment for the conjoined 
tendon, Gimbernat's ligament and triangular ligament. 

The inner border of the body of the pubes presents a rough 
oval facet, which forms a part of the symphysis pubis. 

The outer border of the body of the pubes is thin and affords 
attachment to the obturator membrane. 

Horizontal Ramus. 

The portion of the pubes designated by this name helps to 
form the brim of the true pelvis. It presents for examination 
three surfaces and one extremity. 

The upper surface gives attachment to the pectineus muscle, 
and presents a continuation of the pectineal line and an eminence 
called the pectineal eminence, to which the psoas parvus is attached. 

The under surface presents a groove for the obturator vessels 
and nerve and a sharp margin, which forms a portion of the cir- 
cumference of the obturator foramen. 

The posterior surface forms a part of the anterior boundary 
of the true pelvis. It affords attachment to some of the fibres of 
the obturator internus muscle. 

The outer extremity of the horizontal ramus of the pubes forms 
the pubic portion of the acetabulum, or about one-fifth of the 
whole cavity. 

Descending Ramus. 

This portion of the pubic bone is thin and flattened. It is 



THE PUBES 



"5 



directed downwards and outwards and joins with the ascending 
ramus of the ischium. It presents for examination two surfaces, 
an anterior and posterior, and two borders, an inner and an 
outer. 

The anterior surface is roughened and affords attachment to 
four muscles, viz. : the adductor brevis, the adductor magnus, the 
obturator externus, and the gracilis. 

The posterior surface is smoother than the anterior and af- 
fords attachment to the obturator internus muscle. 

The inner border is rough, thick and everted, especially in the 
female pelvis. It affords attachment to two muscles, the com- 
pressor urethrae and the erector penis or clitoridis, and also to 
the crus penis or clitoridis and to the deep perineal fascia and 
the deep layer of the superficial perineal fascia. 

Its outer border is thin and sharp and affords attachment to 
the obturator membrane. 

Muscles attached to the Os Innominatum. 

The 36 muscles attached to the os innominatum may be clas- 
sified into four sets, as follows : 

(1) The ascending set, comprising 10 muscles. Of these, 5 

form the anterior wall of the abdomen, and 5 form the 
posterior wall of the abdomen. 

(2) The DESCENDING set, comprising 15 muscles. Of these, 9 

are inserted into the femur, and produce shortening 
of the thigh in case of fracture of that bone, and 6 are 
inserted into the bones of the leg. 

(3) The internal set, comprising 5 muscles. These muscles 

all pass towards the median line of the body and form 
the muscles of the perineum and the floor of the pelvis. 

(4) The EXTERNAL set, comprising 6 muscles. These muscles 

all pass directly outzvards from the os innominatum. 
The special muscles included under these various groups are 
shown in the following table : 



The Ascending Set 
(10 muscles.) 



Anterior set (5 muscles) . 1 



'Rectus abdominis. 
Pyramidalis. 

Obliquus abdominis externus, 
Orliquus abdominis internus. 
Transversaus abdominis. 

{Latisstmus dorsi. 
Erector SPIN.®, 
QUADRATUS LUMBORUM, 
Multifddus Spin/s. 
Psoas parvus. 



n6 



SKELETON OF THE TRUNK. 



The Descend 
ing Set. (15 \ 
muscles.) 



Attached to the 
femur. (9 
muscles.) 



Attached to the 
bones of the 
leg. (6 mus- 
cles.) 



f 1 EXSOR 

r T o^Waspect(4)jg™ 

I (~ll TTTT?TTt 



^ To internal aspect (5) 



The internal set (5 muscles) 



The external set (6 muscles) . 



f Tensor vaginae femoris. 

EUS MAXIMUS. 
;s MEDIUS. 

[Gluteus minimus. 
'Iliacus. 

Pectineus. 

Adductor longus. 

Adductor brevis. 

Adductor magnus. 

JSartorius, 
Rectus femoris. 
Gracilis. 
To posterior aspect ( Biceps flexor cruris. 
(ham string mus-(3) ■< Semitendinosus. 
cles.) / Semi meivibranosus. 



Compressor urethra. 
Erector penis. 
Transversus perinei. 
Levator ani. ) forming floor of 
Coccygeus. J pelvis. 
Pyriformis. 
Gemellus superior. 
Obturator internus. 
Gemellus inferior. 
Obturator externus. 
quadratus femoris. 



This arrangement of the muscles attached to the os innomin- 
atum, while it enables the student to recollect their names, serves 
also other purposes. 

I. Thus, the anterior group of the ascending set, arising from 

the upper and anterior borders of the os innominatum, 
are the identical muscles that form the antero-latcral 
wall of the abdomen, and, with one exception, consti- 
tutes the group of muscles connected with the ensi- 
form cartilage of the sternum. 

II. The descending set are the muscles that produce shortening 

of the limb when the neck of the femur is fractured. 

III. The external set are those that produce eversion of the 

foot, in the same accident. 

IV. The internal set are not only the muscles that form the 

floor of the pelvis, but are also those which guide the 
surgeon in operations on the perineum. 

V. The descending and external set, if taken together are the 

muscles which affect the movements of the lower ex- 
tremity on the pelvis. 

VI. By means of these two sets, we can deduce how many 

muscles must be divided in amputation at the hip 
joint. It is evident that the descending and external 
sets, as thus arranged, with the exception of one mus- 
cle, are the only ones that are divided ; so that all we 



THE PEL VIS IN GENERAL. 



117 



have to do is to add the descending set (15) to the ex- 
ternal set (6), and we get 21 muscles, By adding the 
psoas magnus, which does not arise from the os inno- 
minatum, we obtain 22, the number divided in this 
amputation. 

The Pelvis in General. 

The pelvis is usually divided for convenience of description 
into the false and the true pelvis and includes a bony canal which 
is formed by the four bones previously mentioned. 

The FALSE PELVIS comprises that superior expanded portion 
of the ring which corresponds to the iliac fossae. Its walls are 
deficient, in front, between the anterior borders of the ilia and the 
horizontal rami of the pubes, and deficient also, behind, between 
the posterior superior iliac spines and the sacrum. 

The TRUE PELVIS comprised the inferior or constricted portion 
of the ring and presents for examination, 

(1) A brim or inlet. 

(2) A cavity. 

(3) A lower opening or outlet. 

The BRIM or the superior circumference of the true pelvis is 
heart-shaped. It is bounded, in front, by the crest and the spine 
of the pubes, behind, by the anterior border of the base of the 
sacrum and by the sacro-vertebral angle, and, laterally, by the ilio- 
pectineal line. The plane of this opening looks upwards and for- 
wards. Its axis is represented by a line drawn from the umbili- 
cus to the middle bone of the coccyx, and, in an erect posture of 
the body, this axis forms an angle of from 6o° to 65° with the 
horizontal plane, since the base of the sacrum lies about 3f inches 
above the upper border of the symphysis pubis. The diameters 
of this opening vary in the male and female pelvis, the male pelvis 
being the smaller by about one-half an inch in each of the diame- 
ters usually recorded. 

The CAVITY of the true pelvis consists of a short curved canal 
which connects the superior and inferior openings. It is shallow 
in front, and here measures from \\ to 2 inches in height. At its 
middle portion, it is the broadest, and, at its posterior portion, it 
is very deep, since it runs along the concavity of the sacrum and 
of the coccyx, and here measures from 4^ to 5^- inches, in the male 
sex. The antero-postcrior, lateral and oblique diameters of the cav- 
ity of the true pelvis of the male are the same, and average about 
4^ inches in length. 

The lower circumference or OUTLET of the true pelvis is 



Il8 SKELETON OF THE TRUNK. 

bounded, above \ by the public arch, behind, by the tip of the coc- 
cyx, and, laterally, by the tuberosities of the ischia. The lateral 
walls of the outlet are furthermore formed by the sacro-sciatic 
ligaments. The plane of this outlet corresponds to an axis drawn 
from a point, midway between the tuberosities of the ischia, to the 
middle of the base of the sacrum. The coccy-pubic (anteropos- 
terior) diameter in the male sex is usually about 3J inches, while 
the bi-ischiatic (transverse) diameter is usually about 3-| inches. 

Differences in Sexes. 

The bones of the pelvis differ, in their appearance and char- 
acter, in the two sexes. Thus, in the female sex, the pelvic bones 
are much lighter and more slender than in the male, the mus- 
cular impressions are less distinct, the ilia are more expanded, the 
pelvis is broader from side to side, and the iliac spines are more 
widely separated. 

The inlet of the pelvis in the female is much larger than in the 
male and is more nearly circular, since the sacro-vertebral angle 
is much less prominent. 

The cavity is more shallow and more capacious than in the 
male, and the spines of the ischium do not project so far into the 
pelvis. 

The outlet is more expanded and more dilatable, since the coc- 
cyx is anchylosed at a much later date. The pubic arch has a 
wider space, its edges are more everted and the tuberosities of 
the ischia are more widely separated. 

Points of Surgical value. 

The anterior superior sphte of the ilium is employed as a fixed 
point from which measurements of the lower extremity are taken, 
and it is also of value in determining the relative angle of the pel- 
vis to the median line of the trunk, which is often a point of great 
diagnostic value. Pressure upon the two spines is often 'employed 
to detect the existence of fracture of the pelvic bone or of sacro- 
iliac disease. 

The spine of the pubes is a valuable guide in the diagnosis be- 
tween the inguinal and femoral varieties of hernia, and, since it 
lies directly over the external abdominal ring, it serves also as an 
anatomical guide to that opening. This bony prominence also 
lies on a line with the upper border of the trochanter major of the 
femur, in the erect attitude. 



BONES OF THE UPPER EXTREMITY. 



THE SCAPULA. 



121 



BONES OF THE UPPER EXTREMITY. 

The upper extremity is a jointed appendage, which is con- 
nected to the trunk, at its upper portion, while, below that point, 
it is free for the rest of its extent. It is divided into four parts, 
viz., the shoulder, the arm, the forearm, and the hand. 

In the following table are enumerated the bones which assist 
to form each of these various portions. 



'Forming the shoulder (2) j Qavkle 
Forming the arm (1) \ Humerus. 

Forming the forearm (2) \ -J^. 1US " 



The Bones of each of 

Upper Extremities 



the 



thirty-two in number, 
and are situated as 
follows : 



Forming the hand (27)- 



Carpus (8) 



' Scaphoid. 

Semilunar. 

Cuneiform. 

Pisiform. 

Trapezium. 

Trapezoid. 

Os Magnum. 

Unciform. 
Metacarpal bones, (5). 

Phalanges, (14). 

Total, 32 

THE SCAPULA. 

This bone is large in its size and flat and triangular in form. 
It is situated at the back of the shoulder, being often called the 
shoulder blade, and extends from the 2nd to the 7th rib. It pre- 
sents for special description two surfaces, three borders and three 
angles. 

Anterior Surface. 

The anterior surface or venter of the scapula looks towards 
the ribs, is concave and forms the so-called subscapular fossa. 
This fossa is deepest at its upper and outer part, where the sub- 
scapular angle exists, and presents, from within outwards, the 
following points : 

1. A narrow marginal surface, which extends from the supe- 

rior to the inferior angles of the bone and which af- 
fords attachment to the serratus magnus muscle. 

2. Roughened oblique ridges, which converge at the upper and 

outer portion of the bone. These ridges afford attach- 
ment for the subscapularis muscle. 

3. A prominent ridge, which is rounded and which descends 

from the neck of the bone, parallel to its anterior 
border. 



122 BONES OF THE UPPER EXTREMITY. 

4. A deep vertical groove, which affords attachment for the 
lower portion of the subscapularis muscle. 

Posterior Surface. 

The posterior surj T ace or dorsum, of the scapula is divided by a 
bony ridge, called the spine of the scapula, into two unequal por- 
tions. The upper one is called the supra-spinous fossa, and the 
lower one the infra-spinous fossa. 

The posterior surface of the scapula is alternately concave and 
convex, being, from side to side, thrown into alternate ridges and 
depressions. 

The supraspinous fossa is the smaller of the two. It is 
smooth, broadest at its internal portion, and affords attachment 
to the supra-spinatus muscle. 

The infra-spinous fossa is convex at its centre, and concave 
upon either side of its central portion. It presents the following 
points for examination, in addition to two processes, viz., the 
spinous and the acromion. 

1. Internal oblique ridges, for the attachment of the infra- 

spinatus muscle. 

2. A rough apponeurotic ridge, running parallel with the exter- 

nal border of the scapula, which separates the fossa of 
the infra-spinatus muscle from the free edge of the 
bone. 

3. A marginal space, external to the ridge above mentioned. 

This space affords attachment, from above downwards, 
to the teres minor and teres major muscles, and occa- 
sionally to a few fibres of the latissimus dorsi muscle. 
The SPINOUS PROCESS of the scapula is a prominent triangular- 
shaped process, which crosses the dorsum of the scapula obliquely, 
near the line of junction of the upper and the three lower fourths, 
and which is continuous, at its outer extremity, with the acromion 
process. It presents two surfaces and three borders for exami- 
nation. 

The surfaces, are called the upper and lower surfaces of the 
spine. They are both concave and enter into the con- 
struction, respectively, of the supra-spinous and the 
infra-spinous fossae. They afford attachment to the 
supra-spinatus and infra-spinatus muscles. 
The borders are called the anterior, posterior, and external 

borders. 
The anterior border is continuous with the body of the 
scapula. 



THE SCAPULA. 123 

The posterior border is broad and thick, and affords attachment 
to the trapezius muscle, by a ridge of bone termed its 
upper lip, and, by a similar ridge termed its lower lip, 
the deltoid muscle takes its origin. 

The external border is concave in form and is lost, above, upon 
the acromion process, and below, upon the neck of 
the scapula. 

The ACROMION PROCESS, of the scapula projects over the glen- 
oid cavity of that bone, and forms the tip or prominence of the 
shoulder. It is flattened and somewhat triangular in shape and 
presents for examination two surfaces, two borders and an apex. 

The superior surface of this process is subcutaneous and 
roughened for the attachment of a few fibres of the 
deltoid and the trapezius muscles. 

The inferior surface, is concave, smooth, and lies in close re- 
lation to the capsule of the shoulder joint, a bursa 
being usually interposed. 

The outer border affords attachment to the deltoid muscles. 

The inner border affords attachment for the deltoid and trape- 
zius muscles, and also present an oval facet for the 
articulation of the outer extremity of the clavicle. 

The apex affords attachment for the coraco-acromial ligament. 

Borders. 

The borders of the scapula are three in number and are called 
respectively, the superior or cervical border, the external or axil- 
lary border, and the internal or vertebral border. To the latter 
border, the term base of the scapula is often applied. 

The superior border is short and very thin. It presents the 
supra-scapular notch, which is converted into a foramen by a 
transverse ligament, beneath which ligament the supra-scapular 
nerve passes. It affords attachment to the omo-hyoid muscle. 

The axillary border is very thick and affords attachment for 
the long head of the triceps and a part of the subscapularis 
muscle. 

The vertebral border is long, thin, and prominent opposite the 
root of the spinous process. It affords attachment, by its ante- 
rior lip, to the serratus magnus muscle ; by its posterior lip, to 
the supra-spinatus and fnfra-spinatus muscles ; and by the inter 
space between the two, to the levator anguli scapulae the rhom- 
boideus minor and the aponeurosis of the rhomboideus major 
muscle. 



i2 4 bones of the upper extremity. 

Angles. 

The angles of the scapula are three in number and are called, 
respectively, the superior, the inferior, and the external angle. 

The superior a?igle is thin and prominent and affords attach- 
ment for the two first dictations of the serratus magnus muscle, 
and for a few fibres of the levator anguli scapulae and the supra- 
spinatus muscles. 

The inferior angle is thick and rounded and affords attachment 
to the serratus magnus and the teres major muscles. It occasion- 
ally affords attachment to some of the fibres of the latissimus 
dorsi muscle. 

The inferior angle of the scapula corresponds to the level of • 
the seventh dorsal vertebra, and the seventh rib can thus be traced 
from behind forwards, remembering, however, that the head of the 
rib will be i^\t above the tip of the spine of the vertebra, which lies 
obliquely, and therefore not on the same level as the rib. 

At the external angle of the scapula is situated the glenoid 
cavity, called the head, separated by a constricted part called the 
neck of that bone. 

The head of the scapula forms the glenoid cavity, which is 
oval in shape, with its longest diameter directed ver- 
tically. It is shallow, and is deepened and enlarged 
by the glenoid ligament. It articulates with the head 
of the humerus, and affords, by its upper part or apex, 
attachment to the tendon of the long head of the bi- 
ceps muscle. 
The neck of the scapula presents a bony projection, called the 
coracoid process, which affords attachment to three 
muscles, viz., the pectoralis minor, the coraco-brachi- 
alis and the short head of the biceps, and also for three 
ligaments, viz., the conoid, the trapezoid, and the 
coraco-acromial ligaments. 

Muscles attached. 

The scapula affords attachment to 16 muscles, which may be 
classified as follows : 



The Scapula 
affords at- 
tachment to- 
16 muscles 
as follows 



THE CLA VICLE. 



f Supra-spinatus. 

f To dorsal surface (4) J I nfr a-spinatus. 

rTo surfaces. (5) J 1 j; eres min °r- 

L Teres major. 

ITo costal surface. (1) ■{ Subscapulars. 

fTo spinous and aero- j Trapesius. 

To processes .(s)\ mion ( 2 ) ' Deltoid - 

fPectoralis minor. 

To coracoid (3) [-Biceps flexor cubiti. 

[ Coraco-brachialis, 



125 



{To superior border. . . (i) ■{ Omo-hyoid, 
To axillary border.. . . (1) i Triceps extensor cubiti. 
[Rhomboideus minor. 
To vertebral border.. . (3) j Rhomboideus major. 
[Serratus magnus. 
ITo the posterior superior angle (1) \ Levator anguli scapulae, 

Total, 16 

Articulation. 

The scapula articulates with two bones, viz., the humerus and 
the clavicle. 

Development. 

The scapula develops by seven centres of ossification, as fol- 
lows : 

One for the body— which appears at the 8th week of foetal life. 

Two " •' coracoid process — which appears during the 1st year of age. 

Two " " acromion process — " " " " 15th and 16th year of age, 

One " " inferior angle — " " " " 16th " " 

One " " posterior border— " " " " 17th " '• 

THE CLAVICLE. 

The clavicle (clavis, a key) or collar bone, is the most elastic 
bone in the body. It is usually classed as a long bone, although 
in its structure, it resembles rather a short bone. In shape it is 
curved like an italic (/) and is convex, anteriorly, and rounded, in 
the inner two-thirds of the bone. In its outer third, it is anteriorly 
concave, and flattened, from above downwards. 

It presents for examination, first, an inner or cylindrical por- 
tion, second, an outer or flattened portion, third, an inner or 
sternal end, and fourth, an outer or acromial end. 

Inner or Cylindrical Portion. 

This portion of the bone presents for examination the follow- 
ing points : an anterior, a posterior, and a superior border, and 
an anterior, a posterior, and an inferior surface. 

The anterior border is continuous with the anterior border of 
the flattened portion of the bone, and affords attachment to the 
pectoralis major muscle. 



I2 6 BONES OF THE UPPER EXTREMITY. 

The posterior border extends from the rhomboid impression to 
the conoid tubercle, and forms the posterior boundary of the sub- 
clavian groove. 

The superior border is continuous with the posterior border of 
the flattened portion of the bone and affords attachment to the 
sterno-cleido-mastoid muscle. 

The anterior stirface is convex and is continuous with the 
upper surface of the flattened portion of the bone. 

It is covered externally by the platysma muscle, and affords 
attachment, at its inner portion, to the sterno-cleido-mastoid and 
pectoralis major muscles. 

The posterior surface is concave and, at its external portion, 
is narrowed as it becomes continuous with the posterior border 
of the flattened portion of the bone. It frequently gives origin, 
at its inner portion, to some of the fibres of the sterno-cleido- 
mastoid muscle, and, near its centre, it presents the orifice of the 
nutrient canal of the bone, which is directed outwards. 

The inferior surface is narrow at its inner portion, but, exter- 
nally, it is broader and becomes continuous with the under surface 
of the flattened portion of the bone. It presents, from within out- 
wards, the following points : 

I. An articular facet, which articulates with the cartilage of 

the first rib. 

II. The rhomboid impression, for the rhomboid or coraco- 

clavicular ligament. 
III. The subclavian groove, for the subclavius muscle. 

Outer or Flattened Portion. 

This portion of the clavicle presents for examination an ante- 
rior and a posterior border and a superior and an inferior surface. 

The anterior border is thin, concave, and affords attachment 
to the deltoid muscle. 

The posterior border is thick, convex, and affords attachment 
for the trapezius muscle. 

The superior surface is roughened for the deltoid and trape- 
zius muscles. 

The inferior surface presents, at its inner portion, a promin- 
ence of bone, called the conoid tubercle, for the insertion of the 
conoid ligament, and an oblique line for the insertion of the 
trapezoid ligament. 

Inner or Sternal End. 

This end of the clavicle is larger than the shaft of the bone 
and is triangular in form. Its articular facet is continuous with 



THE HUMERUS. 



127 



a facet for the first rib, which is situated at the inner extremity 
of the inferior surface of the bone. The circumference of the end 
of the bone is roughened for the anterior and posterior sterno- 
clavicular ligaments and for the interclavicular ligament. 

Outer or Acromial End. 

This end of the clavicle is flattened, from above downwards. 
It presents a small oval facet, which looks downwards and out- 
wards, and which articulates with the acromion process of the 
scapula. The circumference of this end of the bone is roughened 
for the insertion of the superior and inferior acromio-clavicular 
ligaments. 

Muscles attached. 

The muscles attached to the clavicle or collar bone are six in 
number. These muscles will be found enumerated in the follow- 
ing table : 

' To the anterior surface. . . (2) | ^^ S MAJ ° R ' 

The Clavicle affords at- . 1 Sterno-cleido-mastoid 

tachment to 6 muscles, asj To the posterior surface. . . (2) j Trapesius> 

follows : To the lower surface . (\) \ Subclavius. 

To the external extremity . (1) \ Sternohyoid. 

Total, 6 

Occasionally a few fibres of the platysma muscle arise from 
this bone. 

Development. 

The clavicle begins to ossify sooner than any other bone of 
the body. It is formed from two separate centres, the one for 
the shaft and acromial end appearing about the sixth week of 
fcetal life, the other for the sternal extremity makes its appear- 
ance as an epiphysis, about the 18th or 20th year after birth. 
The epiphysis is united to the shaft at about the 25th year. 

Articulation. 

The clavicle articulates with two bones, viz., the sternum and 
the scapula, and occasionally with the cartilage of the first rib. 

THE HUMERUS. 

The humerus or arm bone, is the longest and largest bone of 
the upper extremity. It presents for examination an upper and 
a lower extremity and a shaft. Each of these portions will be 
separately considered. 



!28 bones of the upper extremity. 

Upper Extremity. 

This portion of the humerus may be divided into 
the following portions: 1st, the head; 2nd, the ana- 
tomical neck ; 3rd, the surgical neck ; 4th, the greater 
tuberosity ; 5th, the lesser tuberosity ; and 6th, the 
bicipital groove. 

The head represents nearly one-half of a sphere, and 
is much more extensive than the corresponding ar- 
ticular surface of the scapula (glenoid cavity). It looks 
upwards, inwards and backwards, and is bounded by a 
constriction in the humerus which is called the ana- 
tomical neck of that bone. 

The anatomical neck is nearly circular in form, ir- 
regular in its outline, and affords attachment to the 
capsular ligament of the shoulder joint. 

It separates the head from the tuberosities. 

The greater tuberosity is a large, rounded eminence 
situated upon the outer side of the bicipital groove. 
It presents, from before backwards, three small facets 
for the attachment of the supra-spinatus, infraspina- 
tus and teres minor muscles. 

The lesser tuberosity is smaller but more prominent 
than the greater, and is situated in front of the head 
of the bone and upon the inner side of the bicipital 
groove. It affords attachment to the subscapulars 
muscle. 

The bicipital groove lies between the tuberosities 
and is comprised in the upper third of the bone. In 
it glides the tendon of the long head of the biceps, 
while to its bottom is attached the tendon of the la- 
tissimus dorsi muscle. It affords attachment, by its 
anterior or outer lip, to the pectoralis major muscle, 
and, by its posterior or inner lip, to the teres major 
muscle. It is deep and narrow above and broad and 
shallow below. 

The surgical neck is that slightly constricted portion 
which joins the upper extremity of the bone to its 
shaft. 
Lower Extremity. 

The lower extremity is slightly curved forwards and 
is flattened from before backwards. It presents for 
examination an articular surface and an inner and 
outer condyle. 



THE HUMERUS. \ 2 g 

The articular surface is longest in the trans- 
verse direction and is sloped obliquely so as to descend 
lower internally than externally. It is also more 
prominent, anteriorly to the condyles. It may be di- 
vided into a radial portion (called also the head) and 
an ulnar portion (called also the trochlear portion). 

The radial portion consists of a small rounded emi- 
nence situated on the front part of the bone. It is 
separated from the trochlear portion of the bone by a 
narrow groove for the inner border of the head of the 
radius, and, at its upper part, is a slight depression 
which receives the head of the radius when the fore- 
arm is flexed. 

The ulnar or trochlear portion occupies the anterior 
and posterior portions of the bone. The inner border 
descends lower than the outer, so that the axis around 
which the ulna rotates is directed downwards and in- 
wards. In front of the trochlea, is a depression called 
the coronoid fossa to receive the coronoid process of the 
ulna, during flexion of the forearm, and, behind the 
trochlea, a depression called the olecranon fossa to re- 
ceive the tip of the olecranon process of the ulna, dur- 
ing extension of the forearm. They are lined by the 
synovial membrane and are separated only by a thin 
plate of bone. Their margins afford attachment to the 
anterior and the posterior ligaments of the elbow joint. 

The INNER CONDYLE, of the humerus is situated a 
little lower than the outer and is more prominent. It 
affords attachment to the internal lateral ligament of 
the elbow joint and also to the following muscles, viz.; 
pronator radii teres, flexor carpi ulnaris, palmaris long- 
us, flexor sublimis digitorum and flexor carpi ulnaris. 

The EXTERNAL CONDYLE, of the humerus is situated 
higher than the inner. It affords attachment to the 
external lateral ligament of the elbow joint and also 
to the following muscles, viz.: extensor carpi radialis 
brevior, extensor communis digitorum, extensor mini- 
mi digiti, extensor carpi ulnaris, anconeus, and the 
supinator brevis. 

Shaft of Humerus. 

This portion of the bone is cylindrical above, while, 
below, it is prismatic and flattened from before back- 



130 



BONES OF THE UPPER EXTREMITY. 

wards. It presents for examination three borders and 
three surfaces. The borders are called respectively, 
the anterior, the internal and the external, while the 
surfaces are named the internal, the external and the 
posterior. 



Borders. 



The anterior border of the shaft of the humerus ex- 
tends from the front of the great tuberosity, above, to 
the coronoid depression, below, and forms the anterior 
or outer lip of the bicipital groove. 

The internal border of the shaft extends from the 
lesser tuberosity of the bone to its internal condyle. 
It forms, at its upper part, the inner or posterior lip 
of the bicipital groove, and, below, it forms the inter- 
nal condyloid ridge. 

At the middle portion of this border is perceived 
the orifice of the nutrient canal of the bone, which is 
directed downwards. 

The external border of the shaft extends from the 
back portion of the greater tuberosity to the external 
condyle. It is less distinct than the two other bor- 
ders and is crossed, above, by the musculo-spiral 
groove. At its lower portion, it becomes more prom- 
inent and forms the external condyloid ridge. 



Surfaces. 



The internal surface is narrower than the external. 
It presents, in its middle portion, a roughened im- 
pression for the attachment of the coraco-brachialis, 
and, towards its lower portion, it frequently presents 
a bony prominence called the supra-condyloid process. 

The external surface is broader than the internal. 
At its middle portion, it presents a rough triangular 
impression for the deltoid muscle, and, below this sur- 
face, it affords attachment to the brachialis anticus 
muscle. 

The posterior surface is somewhat twisted in its 
course. It is crossed, obliquely downwards and out- 
wards, by the musculo-spiral groove, and, above and 
below this groove, it affords attachment to the outer 
and inner heads of the triceps muscle. 



THE HUMERUS. 



131 



Muscles attached. 

The humerus affords attachment to twenty-five muscles, as 
follows : 



The Humer- 
us affords at- 
tachment to 
25 muscles, 
as follows : 



To the upper third 
of bone, (7) 



To greater tuberosity, (3) 
To lesser tuberosity, 
„ To bicipital groove, 



To the shaft of the bone. 



To the lower third 
of the bone, (13) 



' To inner condyle, (5) -< 



To outer condyle, and 
the external con- (8)^ 
dyloid ridge. 



Total, 



supra-spinatus. 
Infra-spinatus. 
Teres minor. 
{i)\ Subscapulars. 

( Pectoralis major. 
(3) < Latissimus dorsi. 
( Teres major. 
f Deltoid. 

J CORACO BRACHIALIS. 
, J BRACHIALIS anticus, 
^ 1 Triceps extensor cu- 

BITI. 

(^SUBANCONEUS. 

f Pronator radii te- 
res. 

Flexor carpi radi- 
alis. 

Palmaris longus. 

Flexor sublimis dig- 

ITORUM. 

Flexor carpi ulna- 

ris. 
'Supinator longus. 
Extensor carpi ra- 

dialis longior. 
Extensor carpi ra- 

dialis brevior. 
Extensor communis 

digitorum. 
Extensor minimi 

digiti. 
Extensor carpi ul- 

NAR1S. 

Anconeus. 
Supinator brevis. 
25 muscles. 



All the muscles which arise from the inner condyle of the hu- 
merus are flexors or pronators, and are situated on the anterior 
surface of the forearm, while those arising from the external con- 
dyle and the external condyloid ridge are extensors and snpina- 
tors, and are situated on the posterior surface of the forearm. 

Development. 

The humerus is developed by seven centres of ossification. One 
of these is for the shaft of the bone, one for the head, 
one for the greater tuberosity, one for the radial artic- 
ular surface, one for the trochlear portion of the artic- 
ular surface, one for the internal condyle, and one for 
the external condyle. 

The centre for the shaft appears very early during 
fcetal life, and ossification extends rapidly towards the 



I32 BONES OF THE UPPER EXTREMITY. 

extremities. At birth, the extremities are cartilagin- 
ous. At about the second year of age, ossification 
commences in the head of the bone, and, about the 
third year of age, the centre for the tuberosities makes 
its appearance. By the fifth year, the head and tuber- 
osities become joined together and so form a single 
epiphysis. 

The lower end of the humerus exhibits ossification 
at the end of the second year, in the radial portion of 
the articular surface. The centre for the trochlear por- 
tion of the articular surface does not appear until 
about the twelfth year of age. At the fifth year of 
age, ossification commences in the internal condyle, 
but the external condyle does not exhibit any trace 
of ossification until the age of thirteen or fourteen 
years. At the seventeenth year of age, the outer 
condyle and the whole articulating surface of the bone 
unite with the shaft ; at eighteen years of age, the in- 
ner condyle becomes united, while the upper epiphysis, 
although the first formed, is not joined to the shaft 
until about the twentieth year of age. 

Articulation. 

The humerus articulates with three bones, as follows : Above 
with the glenoid cavity of the scapula, and, below, 
with the ulna and the radius. 

THE ULNA. 

The ulna is the most internal bone of the fore-arm. It is 
larger and longer than the radius, since it possesses the olecranon 
process and is larger in its upper than its lower portion. It 
may be divided into an upper extremity, a lower extremity 
and a shaft. 

Upper Extremity. 

This portion of the ulna is the largest and strongest portion 
of the bone. It presents two large processes, called the coronoid 
and the olecranon processes, and two depressions, called the 
greater and the lesser sigmoid cavities. 

Processes. 

The CORONOID PROCESS of the ulna is prismatic in 
form and projects forwards towards the anterior sur- 
face of the forearm. It presents for examination an 



THE ULNA, 



133 



apex, a base, and four surfaces, an upper, under, inner 
and outer. 

The apex is curved slightly upwards, and, during 
flexion of the forearm, is received into the coronoid 
fossa of the humerus. 

The base is broad and is continuous with the shaft 
of the ulna. 

The upper surface is concave, from before back- 
wards, and serves the purpose of articulation with the 
humerus. 

The under surface is concave, and is roughened for 
the attachment of the brachialis anticus muscle and 
for the oblique ligament. 

The inner surface is roughened, and is excavated for 
the attachment of the flexor profundus digitorum. It 
presents, anteriorly and from above downwards, the fol- 
lowing points of interest: 1. A prominent bony mar- 
gin for the attachment of the internal lateral ligament 
of the elbow-joint. 2. A tubercle, for the attachment 
of the middle head of the flexor sublimis digitorum. 
3. A ridge, for the attachment of the head of the 
pronator radii teres. 

The outer surface gives origin to a few fibres of the 
supinator brevis, and, above, it forms the lesser sig- 
moid cavity of the ulna. 

The OLECRANON PROCESS of the bone is large in size, 
and is also, like the coronoid process, slightly curved. 

It presents for examination an apex, a base, an an- 
terior, a posterior, and an upper surface, and an inner 
and an outer border. 

The apex is a prominent portion of bone which, 
during extension of the fore-arm, is received into the 
olecranon fossa of the humerus. 

The base is continuous with the shaft of the ulna. 

The anterior surface is concave, and articulates with 
the lower end of the humerus. 

The posterior surface is triangular, and forms the 
point of the elbow, when that joint is flexed. It is 
usually covered by a bursa. 

The upper surface is roughened, at its posterior por- 
tion, for the insertion of the triceps muscle, and, in 
front, close to its margin, it is grooved for the insertion 
of the posterior ligament of the elbow-joint. 



134 



BONES OF THE UPPER EXTTEMITY. 



The two borders present for examination a continua- 
tion only of the grooves, previously mentioned, for the 
internal and posterior ligaments of the elbow-joint. 

The GREATER SIGMOID cavity is embraced between 
the coronoid and olecranon processes of that bone. It 
is divided by a slightly elevated ridge, into two parts, 
the internal of which is the broadest. It articulates 
with the lower end of the humerus. 

The LESSER SIGMOID cavity is situated upon the 
outer side of the coronoid process. It is narrow and 
concave from before backwards. Its extremities afford 
attachment to the orbicular ligament of the radius. It 
articulates with the head of the radius and is covered 
with cartilage. 

Lower Extremity. 

This portion of the ulna is small in size and does 
not participate in the wrist-joint, since it is separated 
by a triangular fibro- cartilage. It presents for exam- 
ination a head, a styloid process, a depression, and a 
groove. 

The head is flattened, at its lower portion, and rest 
upon the triangular fibro-cartilage, but, at its external 
portion, it is semi-cylindrical in form and is received 
into the lesser sigmoid cavity of the radius. 

The styloid process is given off from the inner, and 
back part of the head, and is cylindrical in its form. 
It affords attachment to the ulno-carpal or the internal 
ligament of the wrist-joint. 

Between the head and the styloid process is a marked 
depression for the attachment of the triangular fibro- 
cartilage which separates the ulna from the wrist- 
joint. 

Behind this depression may also be perceived a 
groove, in which plays the tendon of the extensor carpi 
ulnaris muscle. 

Shaft. 

The shaft of the ulna is large and prismatic in form, 
in its upper portion, while, below, it becomes smaller 
and more rounded. It is slightly curved forwards, and, 
at its upper portion, is convex externally, but, below, 
the convexity is most marked at the internal portion 
of the bone. It presents for examination an anterior, 






THE ULNA. 



135 



a posterior, and an external border, and an anterior, a 
posterior, and an internal surface. The borders are 
best marked in the upper two-thirds of the shaft, and 
the surfaces are all three broader in the upper portion 
of the bone than in the lower. 

The anterior border extends from a ridge on the 
inner surface of the coronoid process to the front of 
the styloid process. It affords attachment for the 
flexor profundus digitorum and the pronator quadratus 
muscle. 

The posterior border extends from the lower and 
posterior portion of the olecranon to the back portion 
of the styloid process. It affords attachment, in its 
upper part, to the aponeurosis common to the flexor 
carpi ulnaris, the extensor carpi ulnaris and the flexor 
profundus digitorum muscles. 

The external border divides into two branches, above, 
which form the boundaries of the lesser sigmoid cavity. 
It here embraces a roughened surface, for the attach- 
ment of the supinator brevis muscle. In its middle 
portion it is very prominent, and it here affords at- 
tachment to the interosseous ligament. 

The anterior surface is concave in its upper three- 
fourths, where it affords attachment for the flexor pro- 
fundus digitorum muscle, and, in its lower portion, 
it gives attachment to the pronator quadratus muscle. 
Upon this surface, at the junction of its upper and 
middle third, is perceived the opening of the nutrient 
canal of the ulna, which is directed upwards. 

The posterior surface presents, at its upper portion, 
a triangular surface, bounded externally by an oblique 
ridge. This triangular space affords attachment for the 
anconeus muscle, while the oblique ridge, forming 
its outer border, affords attachment for the supina- 
tor brevis muscle. Below this point the posterior sur- 
face of the shaft is divided by a vertical ridge, into an 
inner portion, which is very narrow, and an outer por- 
tion, which is broad, and which embraces the remainder 
of the surface. The narrow inner portion affords at- 
tachment to the extensor carpi ulnaris muscle, although 
in some instances it is merely covered by it, and the 
outer or broader part affords attachment, from above 
downwards, to the four following muscles, vis, : the 



136 BONES OF THE UPPER EXTREMITY. 

supinator brevis, the extensor ossis metacarpi pollicis, 
the extensor secundi internodii pollicis, and the exten- 
sor indicis. 

The internal surface is subcutaneous in its lower 
fourth, and, in its upper three-fourths, it affords attach- 
ment to the flexor profundus digitorum muscle. 

Muscles Attached. 

The ulna affords attachment to thirteen muscles, which may- 
be found classified below. 

f To olecranon process {f)\ Triceps extensor cubiti. 

{Brachialis anticus. 
Pronator radii teres. 
Flexor sublimis digitorum. 
To internal and an- \ Pronator quadratus. 

terior surface (2) ] Flexor profundus digitorum. 

r Anconeus. 
Supinator brevis. 
Extensor ossis metacarpi pollicis. 
Extensor secundi internodii pollicis. 
^ Extensor indicis. 

N \ Flexor carpi ulnaris. 
posterior border. (2) ^ ExTEN < 

Total, 13 muscles. 



The Ulna af- 
fords attach- 
ment to 13 < 
muscles, 1 
follows : 



To posterior surface (5) 






Occasionally the flexor longus pollicis is attached to the 
ulna. 






Articulation. 

The ulna articulates with two bones, namely, the humerus and 
the radius. 

Development. 

The ulna is developed by three centres of ossification : one for 
the shaft of the bone, one for the inferior extremity and one for 
the olecranon process. In the shaft of the bone, ossification com- 
mences, at about its centre, during the fifth week of foetal life 
and rapidly extends through its greater portion. At birth, the 
ends of the ulna are cartilaginous. At the fourth year of age, 
a separate osseous nucleus makes its appearance in the centre of 
the head of the ulna and from this point ossification rapidly ex- 
tends into the styloid process. The olecranon process does not 
begin to ossify until about the tenth year of age, when the shaft 
of the bone shows a tendency to extension into it. At about 
the sixteenth year of age, the upper epiphysis of the bone becomes 
fully joined to the shaft, but the lower one does not become united 
until about the twentieth year. 



the radius. 137 

The Radius. 

The radius is the external of the two bones of the fore-arm, 
and is so called from its resemblance to the spoke of a wheel. It 
is small above, where it forms a small part of the elbow joint, 
and large below where it enters largely into the structure of the 
wrist joint. It is prismatic in form and curved, the convexity of 
the bone looking outwards, in order to afford more powerful lever- 
age to the pronator radii teres muscle and to increase the breadth 
of the fore-arm. It presents for examination, 1st, an upper ex- 
tremity, 2nd, a lower extremity, 3rd, a shaft. 

Upper Extremity. 

This is smaller than the lower extremity. It pre- 
sents the following points of interest, 1st, a head, 2nd 
a neck, 3rd, a tuberosity. 

The head of the radius is cylindrical in form and 
cup-shaped above. The cup articulates with the 
lesser head of the humerus, and the inner and 
broader edge of the head corresponds to the groove 
between the lesser head of the humerus and the 
trochlea. The inner and broader part of the cylin- 
drical surface of the head articulates with the lesser 
sigmoid cavity of the ulna, while the outer narrower 
part plays within the orbicular ligament. 

The neck of the radius is that constricted and 
rounded portion of the bone which supports the head. 
On its posterior surface, it presents a slight ridge for 
the attachment of the supinator brevis. 

The tuberosity of the radius is situated at the lower 
and inner part of the neck. It is rough behind for 
the insertion of the biceps muscle, and in front, it is 
smooth and is covered by a bursa. 

The tubercle of the radius can be felt only on ex- 
treme pronation of the hand and on the posterior sur- 
face of the fore-arm, slightly below the head of the 
bone. The head of the radius can be felt to rotate at 
a depression in the skin, just below the bend of the 
elbow upon the posterior surface of the forearm, when 
the forearm is extended. This point is o( surgical 
value in deciding upon a possible displacement of the 
head of that bone. 



!38 bones of the upper extremity. 

Lower Extremity. 

This portion of the radius is large, thick and quad- 
rilateral in form. It presents for consideration five 
surfaces, two of which are articular, viz., the lower and 
the inner, and a styloid process. 

The inferior surface is concave, triangular in shape, 
and is divided by a slight ridge, running from before 
backwards, into an outer, large, triangular portion for 
articulation with the scaphoid bone, and an inner, small 
portion which is quadrilateral and which articulates 
with the semilunar bone. 

The internal surface or sigmoid cavity of the radius 
is narrow, concave, and articulates with the head of 
the ulna. 

The anterior surface is excavated and affords at- 
tachment to the pronator quadratus. Its lower margin 
is prominent and affords attachment to the anterior 
ligament of the wrist joint. 

The external surface is prolonged downwards into 
a bony prominence called the styloid process. This 
process is thick and conical in shape, and affords at- 
tachment, at its base, to the supinator longus, and, at 
its apex, to the radio-carpal or external lateral liga- 
ment of the wrist joint. 

On the outer surface of this process, is a shallow 
groove directed obliquely downwards and forwards 
and divided into two grooves by a slight bony ridge. 
The anterior groove transmits the tendons of the ex- 
tensor ossis metacarpi pollicis and the posterior groove 
transmits the tendon of the extensor primi internodii 
pollicis, both of which muscles are enclosed in one 
synovial sheath. 

The posterior surj ? ace is convex and gives attachment, 
below, to the posterior ligament of the wrist joint. 
It presents, from without inwards, the following points 
of interest. 

1. A broad and shallow groove which transmits the 
tendons of the extensor carpi radialis longior and the 
extensor carpi radialis brevior muscles, both of which 
are enclosed in one synovial sheath. 

2. A narrow and deep groove for the extensor secundi 
internodii pollicis. 

3. A broad and shallow groove for the extensor in- 



THE RADIUS. 



139 



dicis and the extensor communis digitorum, both of 
which are inclosed in one synovial sheath. 

4. A half groove, which is completed by the head of 
the ulna and which transmits the extensor minimi 
digiti and its sheath. 
Shaft. 

This portion of the radius is slightly concave, in 
front, and, in its upper portion, is small and rounded ; 
while, lower down, it becomes larger and prismatic. 
It presents an anterior, a posterior, and an internal 
border, and an anterior, a posterior, and an external 
surface. 

The anterior border extends from in front of the 
tuberosity to the base of the styloid process. It is 
prominent in its upper portion, where it forms the so- 
called oblique line of the bone, and it gives attachment 
to the supinator brevis, the flexor sublimis digitorum 
and the flexor longus pollicis muscles. In its lower 
portion, it affords attachment for the pronator quad- 
ratus muscle. 

The posterior border extends from the back of the 
neck of the bone to the posterior portion of the sty- 
loid process. It is most distinct in its middle third. 

The internal border extends from the back of the 
tuberosity to the sigmoid cavity, where it bifurcates. 
It is sharp and very distinct in its middle third, and 
affords" attachment to the inter-osseous ligament. 

The anterior surface is narrow and concave, in its 
upper three-fourths, and broad and concave in its lower 
fourth. It affords attachment to the flexor longus pol- 
licis, in the upper portion of the bone, and to the 
pronator quadratus, in its lower fourth. It presents a 
little above its middle the orifice of the nutrient fora- 
men. 

The posterior surface is narrow and rounded in its 
upper portion and broad and convex in its lower por- 
tion. It affords attachment, at its upper part, to the 
supinator brevis muscle, and, at its middle portion, 
where it is rough and slightly concave, to the extensor 
primi internodii pollicis and a few fibres of the exten- 
sor ossis metacarpi pollicis. 

The external surface is convex and affords attach- 
ment, in its upper portion, to the supinator brevis 



140 



BONES OF THE UPPER EXTREMITY. 



muscle, and, at its middle portion, it presents a rough 
impression for the pronator radii teres muscle. 

Muscles Attached. 

The radius affords attachment to nine muscles which 
may be arranged as follows : 

To its tubercle {f)\ Biceps flexor cubiti. 

rp ., . • r ,, ( Flexor sublimis digitorum. 

To ^anterior surface. . (2) | Flexqr lonqus poLLICIS> 

f Extensor ossis metacarpi 

rr, ■ '., . . ■ r , N ) POLLICIS. 

To its posterior surface. (2W ExTENSOR pRIMI INTERN0DII 

[ POLLICIS. 

f Supinator brevis. 

™ ., , ,, , / x I Pronator radii teres. 

I To its external border. . . (4 k 



The Radius affords at- 
tachment to 9 mus- 
cles, as follows : 



Total, 9 



Pronator quadratus. 
• ^ Supinator longus. 



Development. 

The radius is developed by three centres of ossification : one 
for the shaft, one for the upper extremity, and one for the lower 
extremity. The centre for the shaft of the bone appears, near its 
middle, at about the eighth week of fcetal life. At birth, the ends 
of the bone are cartilaginous, but the shaft is almost completely 
ossified. About the end of the second year, the lower epiphysis 
appears, and about the fifth year of age, the upper epiphysis. The 
upper epiphysis unites with the shaft at the age of puberty, but 
the lower epiphysis does not become united until the twentieth 
year of age. 
Articulation. 

The radius articulates with four bones, namely, the humerus, 
the ulna, the scaphoid, and the semilunar. 

THE HAND. 
The bones which compose the hand may be subdivided into 
three parts, viz., the carpus, the metacarpus, and the digits. The 
following table will show the situation of the twenty-seven bones 
which are included in the hand : 



Carpus. 



(3) 



f Scaphoid. 
fin proximal row. ( 4 )j Sform. 
[_ Pisiform. 



The Hand is composed \ 
of twenty-seven bones, \ 
as follows : 



.In distal row. 



(4) 



f Trapezium. 
J Trapezoid, 
j Os magnum. 
I Unciform. 



I Metacarpus (5) 

v. Phal3ncrp<; (\,\\ 



Phalanges (14) 

Total, 27 bones. 



BONES OF THE CARPUS. 141 

BONES OF THE CARPUS. 

The carpal bones are eight in number and are divided into two 
rows of four bones each. The bones which enter into the forma- 
tion of the upper row are thus named, from without inwards, trans- 
versely across the wrist. I, the scaphoid, 2, the semilunar, 3, the 
cuneiform, 4, the pisiform. 

The bones which comprise the second row of the carpus may 
be thus enumerated in their order from without inwards. 1, the 
trapezium, 2, the trapezoid, 3, the os-magnum, 4, the unciform. 

The SCAPHOID BONE is named from its resemblance to the shape 
of a boat, being broad at one end, narrowed at the other like a 
prow and convex upon one side. It presents a narrow extremity 
which is called its tuberosity, and which may be felt at the back of 
the wrist, on the inner side of the extensor tendons of the thumb, 
a broad end, a convex and a concave surface, a convex and a con- 
cave border. It articulates with five bones, viz., the semilunar 
bone, the trapezium, the trapezoid, the os magnum, and the radius. 

The SEMILUNAR BONE is so called from a cresentic cavity and a 
somewhat cresentic outline. It presents four articular surfaces a con- 
cave, a convex, and two lateral, and two surfaces which are called 
the dorsal and the palmar. It articulates with five bones, viz., the rad- 
ius, the scaphoid, the os magnum, the cuneiform, and the unciform. 

The CUNEIFORM is wedge-shaped, and is best distinguished 
from the other carpal bones by an isolated facet for the articulation 
of the pisiform bone. It presents three surfaces, a rough, a con- 
cave, and a smooth, a base, which is articular, and an apex, which 
is rough and pointed. It articulates with three bones, viz., the 
semilunar, the pisiform, and the unciform. 

The PISIFORM BONE may be recognized by its small size and 
by possessing a single articular facet. It is the smallest of the 
bones of the carpus, is of an ovoid form and is placed ver- 
tically in front of the cuneiform bone, where it can be felt upon 
the palm of the hand, just beloiv the ulna. It possesses four sides 
and two extremities. One of these sides is articular, one rounded, 
one concave and one convex in form. It articulates with one bone 
only, viz., the cuneiform bone. 

The TRAPEZIUM is very irregular in shape, but it may be dis- 
tinguished by a deep groove for the tendon of the flexor carpi 
radialis muscle. It possesses three surfaces, one articular and one 
oval in form, the other marked by three facets and three rough 
borders. It articulates with four bones, viz., the scaphoid, the 



142 



BONES OF THE UPPER EXTREMITY. 



trapezoid, the metacarpal bone of the thumb and the second 
metacarpal bone. 

The TRAPEZOID BONE is small, oblong and quadrilateral. It 
is bent upon itself near its middle portion and possesses four ar- 
ticular surfaces and two non-articular, one of which is large and 
broad and is called the dorsal, the other is small and rough and is 
called the palmar. 

It articulates with /our bones, viz., the scaphoid, the trapezium, 
the os magnum and the second metacarpal bone. 

The OS MAGNUM possesses six surfaces, viz., an anterior, pos- 
terior, superior, inferior, external, and internal. It is sometimes 
subdivided into a head, neck, and body. It is the largest bone of 
the carpus and is sometimes dislocated, when it appears as a tumor 
on the dorsal aspeet of the hand in the line of the metacarpal bone 
of the middle finger. It articulates with seven bones, viz., the scap- 
hoid, semilunar, trapezoid, unciform, and the second, third, and 
fourth metacarpal bones. 

The UNCIFORM BONE is triangular and is remarkable for a long 
and curved process which projects from its palmar aspect. It 
possesses five surfaces, three of which are articular and two free. 
It articulates with five bones, viz., the semilunar, the cuneiform, 
the os magnum, and the fourth and fifth metacarpal bones. 

Articulation of the Carpus. 
The following diagram illustrates the various articulations of 
each of the eight carpal bones. 




Proximal Row. 
Articulation. 



S S C 
5- 5- 3- 



BONES OF THE CARPUS. 



143 



In this diagram the black dots indicate the carpal bones in 
their relation to each other and the bones of the forearm. The 
connecting lines indicate the points of articulation of each part in 
the diagram, so that by tracing all the lines from any given part 
the articulation of that part can easily be ascertained. 

It is easy to recognize whether any bone of the carpus belongs 
to the right or left side, when it is placed in position by the fol- 
lowing guides : 

Scaphoid. 

1. The largest articular facet is above. 

2. The tubercle is on its outer side. 

3. The transverse groove is behind. 
Semilunar. 

1. The convex articular facet is above. 

2. The largest rough surface is in front. 

3. The semilunar facet is on its outer side. 
Cuneiform. 

1. The convex surface is directed upwards. 

2. The flat surface lies in front. 

3. The small surface or angle lies on the inner side. 
Pisiform. 

1. The articular facet lies posteriorly. 

2. The concave surface lies on the inner side. 
Trapezium. 

i. The saddle-shaped articular facet lies below. 

2. The ridge is directed forwards. 

3. The rough lateral surface is directed outwards. 
Trapezoid. 

1. The saddle-shaped articular facet looks downwards. 

2. The large rough surface lies posteriorly. 

3. The projecting part lies on the inner side. 
OS MAGNUM. 

1. The head of the bone looks upward. 

2. The large rough surface lies posteriorly. 

3. The tubercle of the base lies on the inner side. 
Unciform. 

1. The unciform process lies in front and near its 

lower part. 

2. The concavity of the bone is directed outwards. 

METACARPAL BONES. 
The bones of the metacarpus are five in number, and are 



! 4 4 BONES OF THE UPPER EXTREMITY. 






named in numerical order from the external or radial side of the 
hand, 1st, 2d, 3d, 4th, 5th. They are classed as long bones, and 
are divisible into a head, shaft and base. The head is directed 
towards the fingers while the base articulates with the carpal 
bones. 

The head is rounded at the extremity, and, at each side, is 
flattened for the insertion of strong ligaments. 

The shaft is prismoidal in shape and, on each side, is deeply 
marked for the attachment of the interossei muscles. 

The base is quadrilateral and roughened for the insertion of 
tendons and ligaments. It possesses three articular surfaces, one 
at each side for the adjoining metacarpal bones, and one at the 
extremity for articulation with the carpus. 

The metacarpal bone of the thumb is one third shorter than 
the rest ; the articular surface of the head is less round, and the 
base has a single articular surface which joins the trapezium. 

The metacarpal bones of the different fingers may be thus dis- 
tinguished from each other: 

In the index finger, the base is very large and has four articular 
surfaces. 

In the middle finger, a projecting process exists upon the radial 
side of the base, and two small facets upon its ulnar lateral surface. 

In the ring finger, the base is small and square and possesses 
two small circular facets, which correspond with those of the 
middle metacarpal bone. 

In the little finger, the metacarpal bone has only one lateral 
articular surface. 

Articulations of the Metacarpal Bones. 
The metacarpal bones articulate, at their bases, as follows: 

ist Metacarpal bone, with one bone, \ Trapezium. 

{Trapezium. 
Trapezoid. 
Os MAGNUM. 

3rd Metacarpal bone, with one bone, \ Os Magnum. 

4th Metacarpal bone, with two bones, \ 3D METACARPAL - 

^ ' ' r5 TH METACARPAL. 

5TH Metacarpal bone, with one bone, \ Unciform. 

The head of each metacarpal bone articulates, however, with a 
phalanx. 

Muscles Attached to Metacarpal Bones. 
All the flexors and extensors of the wrist joint, with the ex- 
ception of the palmaris longus, are inserted into the base of a 
metacarpal bone. 



THE PHALANGES Iz K 

The metacarpal bone of the thumb affords attachment to three 
muscles, viz., the flexor ossis metacarpi pollicis, the extensor ossis 
metacarpi pollicis and the first dorsal interosseous. 

The metacarpal bone of the index fi?iger affords attachment to 
five muscles, viz., the extensor carpi radialis longior, the flexor 
carpi radialis, the first and second dorsal interossei and the first 
palmar interosseous muscle. 

The metacarpal bo?ie of the middle finger affords attachment to 
four muscles, viz., the extensor carpi radialis brevior, the ad- 
ductor pollicis and the second and third dorsal interossei mus- 
cles. 

The 7netacarpal bone of the ring finger affords attachment to 
three muscles, viz., the third and fourth dorsal interossei and the 
second palmar interosseous muscle. 

The metacarpal bone of the little finger affords attachment to 
five muscles, viz., flexor carpi ulnaris, the extensor carpi ulnaris 
the opponens minimi digiti, the fourth dorsal and the third palmar 
interosseous muscles. 

Phalanges. 

The phalanges are the bones of the fingers. They are named 
from their arrangement in rows the first, second and third, from 
the metacarpal bone forwards, and are fourteen in number, — 
three to each finger, and two to the thumb. They are classed as 
long bones and are divisible into a shaft and two extremities. 

The shaft is compressed from before backwards, convex on its 
posterior surface, and, in front, is flat with raised edges. 

The metacarpal extremity of the first row of phalanges is a 
simple concave articular surface, but of the other two rows, it con- 
sists of a double concavity separated by a slight ridge. 

The digital extremities of the first and second rows of pha- 
langes present a pulley-like surface, which is concave in the middle 
and convex upon either side. The terminal extremity of the 
phalanx of each finger is broad, rough and expanded into a semi- 
lunar crest. 

Muscles Attached to the Phalanges. 

The deep flexor of the fingers in common is attached to the 
third phalanges, the superficial flexor of the fingers in common is 
inserted into the second phalanges, and the common extensor of 
the fingers is attached to the second and third phalanges. 

In the thumb, the first phalanx affords attachment to four 
muscles, viz., the adductor pollicis, the flexor brevis pollicis, the 



I4 6 BONES OF THE UPPER EXTREMITY. 

abductor pollicis and the extensor primi internodii pollicis ; and 
the second phalanx to two muscles, viz., the flexor longus pollicis 
and the extensor secundi internodii pollicis. 

In the second, third and fourth fingers, the first phalanx affords 
attachment to one dorsal and one palmar interosseous muscle, 
and, in the little finger, the first phalanx affords attachment to 
the abductor minimi digiti, the flexor minimi digiti and one 
palmar interosseous. 

In all of the fingers, save the thumb, the second phalanges 
afford attachment to the flexor sublimis digitorum and the ex- 
tensor communis digitorum, while the last phalanges of these 
fingers afford attachment to the flexor profundus digitorum and 
the extensor communis digitorum muscles. 



BONES OF THE LOWER EXTREMITY. 



THE FEMUR. 



149 



BONES OF THE LOWER EXTREMITY. 

The skeleton of the lower extremity, as before stated, com- 
prises thirty bones. 

Each lower extremity is composed of three segments, viz. ; 

1. Thigh. 

2. Leg. 

( Tarsus. 

3. Foot. •< Metatarsus. 

( Digits. 

The thigh is constituted by one bone, viz., the femur. 

The leg is composed of three bones, viz., the patella, the tibia, 
and the fibula. 

The foot has three segments and twenty-six bones, viz., 1. tar- 
sus, seven bones ; 2. metatarsus, five bones ; 3. digits, fourteen 
bones, (phalanges.) 

FEMUR. 

The femur is a long bone, divisible, like other bones in the 
same class, into a shaft, a superior and an inferior extremity. 

Upper Extremity. 

This portion of the bone presents for examination. 1. a head, 
2. a neck, 3. a great trochanter, 4. a lesser trochanter. 

The head forms nearly two-fifths of the sphere and presents a 
small depression for the attachment of the ligamentum 
teres. 

The neck is situated between the head and the trochanter and 
is longest and most inclined in youth, growing shorter 
and more horizontal as age advances. It is a quad- 
rangular process of bone, directed inwards, upwards, 
and a little forwards. It is flattened, from before 
backwards, so that it is much greater in the vertical 
than in the antero-posterior direction. In adult life it 
forms an angle of I20°-I25° with the shaft. 

The greater trochanter is large, quadrilateral in shape, and is 
most prominent posteriorly. To its outer surface is 
attached the gluteus medius muscle. Its inner sur- 
face presents the so-called digital fossa for the inser- 
tion of the obturator externus muscle. Its upper bor- 
der affords attachment for the obturator interims, the 
two gemelli and the pyriformis muscles. Its anterior 
border affords attachment for the gluteus minimus 



I 5 O B ONE S OF THE L O WER EX TRE MI T Y. 

muscle. The so-called intertrochanteric line of the 
femur extends from the greater trochanter to the 
lesser, and forms the inferior boundary of the neck of 
the bone. 
The lesser trochanter is small and conical in shape and affords 
attachment to the psoas and iliacus muscles. 

Lower Extremity. 

The lower extremity of the femur is broad and is expanded 
into two prominent processes, called the external and 
internal condyles, separated by a notch, behind, called 
the inter-condyloid notch which lodges the two crucial 
ligaments. 

Of these two condyles, the outer is the broadest and 
longest, so that if the bone be placed vertically it pro- 
jects full one-half inch below the inner, since the shaft 
of the bone is directed inwards towards the median line 
and therefore requires additional length upon that side. 

The outer condyle affords attachment for the exter- 
nal lateral ligament of the knee-joint, the popliteus 
muscle, and the gastrocnemius muscle. 

The inner condyle affords attachment for the inter- 
nal lateral ligament of the knee-joint, and the inner 
head of the gastrocnemius muscle. 

The points of bone upon either condyle of the 
femur, called the tuberosities of the condyles, give at- 
tachment to the lateral ligaments. They are situated 
behind and not in front of the centre of motion. 

Shaft. 

The shaft of the femur is rounded in front and covered with 
muscles, but behind it is raised into a rough and prom- 
inent ridge called the linea aspera. Of all the bones 
in the body it most nearly resembles a cylinder. It is 
not quite straight, but is slightly curved in front. At 
the lower extremity of the bone, the linea aspera di- 
vides into two ridges, called the external and internal 
condyloid, which descend to the two condyles of the 
femur and enclose a triangular space, called the popli- 
teal space, upon which rests the popliteal artery, while, 
above, two lines can be traced from the linea aspera to 
the trochanters. The internal condyloid ridge is less 
marked than the external, and presents a broad and 
shallow groove, for the passage of the femoral artery. 



THE FEMUR. 



KI 



The nutrient foramen is situated in or near the linea 
aspera : at about one-third from its upper extremity, 
and is directed obliquely from, below upwards. 

Muscles Attached to the Femur. 



The 
follows : 



femur affords 



Is attachment to 


twenty- thr 


ee muscles, as 


To its upper fifth, 


IO 




To its shaft, 


IO 




To its lower fifth, 


3 




Total, 


23 





Occasionally the tensor vaginae femoris muscle takes its origin 
from the femur, in which case the total of muscles reaches twen- 
ty-four. The following table illustrates the points of attachment 
of these twenty-three muscles : 



'Attached to the greater trochanter. 



(8) 



To the lesser trochanter (2) 



The Fe- 
mur af- 
fords at- 
tachm' W To the shaft. ■{ 
to 23 
muscles 
as fol- 
lows : .» 



Gluteus medius. 
Gluteus minimus. 
Pyriformis. 
Gemellus superior. 
Obturator internus. 
Gemellus inferior. 
Obturator externus. 
^ Quadratus femoris. 
Psoas magnus. 
Iliacus. 



{Anterior surface (2) j 



Posterior sur- 
face. 



(8). 



Sub-crureus. 

r T . , v \ Vastus externus. 

I Linea aspera (2) \ , r t 

r v ' 1 Vastus internus. 

f Gluteus maximus. 
I Pectineus. 



Interstices, 



_ To lower fifth 



,,v J Biceps flexor cruris. 
\ Adductor longus. 
j Adductor magnus. 
^ Adductor brevis. 

i Gastrocnemius, 
Plantaris. 
Popliteus. 



Total, 23 

Articulations of the Femur. 

The femur articulates with three bones, namely : the os inno- 
minatum, the tibia, and the patella. 

Development of the Femur. 



This bone is developed by five centres of ossification, which 
are distributed as follows : 



I 5 2 BOXES OF THE LOWER EX TREMITY. 

(i) One for the shaft and tuck, which appears at the 5th month of foetal life. 



(2) " 


" " lower extremity. 


" 


.. g:h u 




• • Asw'of the bone. 


u 


" end of 1st vear of age 


(4) " 


•' greater trochanter, " 


« 


•' s± - " 


(5) " 


" u l<s:ir trochanter^ " 


" 


•• 14th " ■ 



BOXES OF THE LEG. 

The bones of the leg are three in number, viz. : 

1. The patella, or knee-pan. 

2. The tibia, or shin-bone. 

3. The fibula. 

If the patella be recognized as a distinct bone, for it is often 
classed as one of the sesamoid bone, it affords attachment to four 
muscles, viz. : 

Rectus femoris. 
Vastus externus. 
Crureus. 
Vastus internus. 

The patella is a triangular-shaped bene and presents two sur- 
faces, called the anterior and the posterior surfaces, a base, which 
looks upwards, and an apex, which looks downwards. 

The posterior surface has a ridge dividing it into two portions. 

The anterior surface is convex and is perforated with numer- 
ous apertures, through which pass the nutrient vessels of the 
bone. 

The base of the bone is that border which is directed upwards 
and which affords attachment for the muscles mentioned above. 

The apex of the bone is that border which is directed down- 
wards and which affords attachment to the iigamentum patellae. 

The patella articulates with one bone, viz., the femur. It also 
enters into the formation of the knee-join:. 

TIBIA. 

The tibia, or shin-bone, is the large bone of the leg. It is 
prismoidal in form and is divisible into a shaft, an upper and a 
lower extremity. 

Upper Extremity. 

The upper extremity or head of the tibia is of large 
size and is expanded upon either side into two bony 
projections called the tuberosities of the tibia. 

The upper surface of the head and tuberosities artic- 
ulates with the condyles of the femur. The articular 
surface upon the inner tuberosity is oval in shape, and 






Shaft. 



the tibia. 153 

that upon the external tuberosity is broad and nearly 
circular. 

On the upper surface of the tibia, between its two 
articular surfaces, is a projection of bone called its 
spinous process, and, behind this process, a rough de- 
pression for the attachment of the crucial ligaments of 
the knee-joint. 

On the anterior aspect of the head of the tibia, be- 
tween the two tuberosities, is a prominent elevation 
of bone called the tubercle, for the insertion of the lig- 
amentum patellae. 

Posteriorly, the tuberosities are separated by a shal- 
low notch, called the popliteal notch, which affords 
attachment for the posterior crucial ligament. 



The shaft of the tibia presents three surfaces : an 
internal, w r hich is subcutaneous and superficial ; an ex- 
ternal, which is concave and marked by a sharp ridge 
for the insertion of the interosseous membrane, and 
a posterior, which is grooved for the insertion of 
muscles. 

Upon the posterior surface, near the upper extremity 
of the bone, is an oblique ridge called the popliteal line, 
which affords attachment to the fascia of the popliteus 
muscle, and, below this line, the orifice of the nutrient 
canal is perceived, which is directed downwards. 

Lower Extremity. 

This portion of the tibia is prolonged, on its inner 
side, into a large process, called the internal malleolus. 
Upon the outer side, the lower extremity of the tibia 
is concave and triangular in form. It articulates, on 
its outer surface, with the other bone of the leg, viz., 
the fibula, and, at its extremity, with the astragalus, 
one of the bones of the tarsus. 

Muscles Attached to Tibia. 

The muscles attached to the tibia are fourteen in number. 
They may be thus classified : 



154 BONES OF THE LOWER EXTREMITY. 

{ Rectus femoris. 

To the tubercle (4) J Y astus extern ^. 

v ' J Lrureus. 

[Vastus internus. 
f Sartorius. 

^To the internal surface, U)\ ^racps: _ 

v ^ 7 i bemitendinosus. 



f To the upper 

END (8) 



The tibia af- 



fords attach- J ^ Semimembranosus 



ment to 14 
muscles, 
follows : 



[To the shaft, (6)* 



Tibialis anticus. 
' To the external surface, (2) -I Extensor longus dig- 

itorum. 
'Popliteus. 
Tibialis posticus. 
Soleus. 

Flexor longus digi- 
torum. 



^ To the posterior surface, (4) 



Total, 14 

Of these fourteen muscles, the first four are indirectly attached 
to the tibia, by means of the ligamentum patellae, and only five of 
the fourteen muscles arise from the bone, the rest making it their 
point of insertion. 

The tibia has the largest nutrient foramen of any bone in the 
body. 

Articulations of Tibia. 

The tibia articulates with three bones, viz., the femur, the 
fibula, and the astragalus. It enters into the formation of two 
joints, viz., the knee and ankle joints. 

Development. 

The tibia develops by three centres of ossification, viz., one for 
the shaft, and one for each extremity. That for the shaft appears 
about the 5th week of fcetal life, that for the upper extremity 
about the time of birth, and that for the lower extremity at about 
the second year. 

FIBULA. 

The fibula is a long and slender bone, prismoidal in shape and 
divisible into a shaft and two extremities. 

Upper Extremity. 

This portion of the bone is termed its head. It is 
thick and large, and marked by a concave surface 
which articulates with the external tuberosity of the 
tibia. At its external portion, is perceived a thick and 
rough prominence, to which is attached the external 
lateral ligaments of the knee-joint, and, behind, a pro- 
cess, called the styloid process, exists for the insertion 
of the tendon of the biceps muscle. 



THE FIBULA. 



155 









The head of the fibula is one of the prominent bony 
points of the knee, and lies about on the same level as 
does the tubercle of the tibia. 
Lower Extremity. 

This portion of the fibula forms the external malle- 
olus. On its inner surface is a triangular facet for artic- 
ulation with the astragalus. The posterior portion is 
grooved for the tendons of the peronei muscles. 
Shaft. 

The shaft of the fibula presents three surfaces, an 
external, internal, and posterior, and three borders. 

The external surface affords attachment to the two 
peronei muscles. 

The internal surface is marked, along its middle por- 
tion, by the interosseous ridge for the attachment of 
the interosseous membrane. 

The posterior surface is twisted and presents, at 
about its middle, the nutrient foramen of the bone 
which is directed downwards. 

The shaft of the fibula arches backwards, in direct 
contrast with the shaft of the tibia, and affords little 
if any assistance in supporting the weight of the body. 
The difference in the curve of the shafts of the two 
bones of the leg has a practical value in performing 
amputations in this region, since the direction of the 
flap incisions is modified in accordance with it. 

Muscles Attached to Fibula. 
The fibula affords attachment to nine muscles, as follows : 

'To the styloid process . . . (i)-{ Biceps flexor cruris. 

I Extensor longus digitorum 
To the anterior surface, (3) < Extensor proprius pollicis. 
( Peroneus tertius. 
.Sole 
To the posterior surface, 

pollicis. 



The Fibula affords attach 
ment to 9 muscles, as fol-^ 
lows : 



iSoleus. 
Tibialis posticus. 
Flexor longus pol 

L-To the external surface, (2) \ ^^ J™*?*- 
J ( 1 eroneus brevis. 



Articulations of Fibula. 

The fibula articulates with only two bones, vis., the tibia and 
the astragalus. 
Development of Fibula. 

The fibula is developed by three centres of ossification ; one for 
the shaft, and one for each extremity. In the fibula, the centre 






156 BONES OF THE LOWER EXTREMITY. 

for the shaft appears rather later than in the tibia; that for the 
lower extremity appears in the second year; and that for the 
upper, not until the fourth year of age. 

In this bone, the portion exhibiting the first trace of ossifica- 
tion is the first to unite, being situated in the lower end of the 
bone, or in the external malleolus. This is an exception to a 
general law of ossification, but is still an observance of that law 
which is governed by the direction of the nutrient canal. 

General Summary. 

I. Of the twenty-three muscles attached to the femur, 

16 move the thigh on the trunk and vice-versa. 
6 move the leg upon the thigh and vice-versa. 
I moves the foot upon the thigh and vice-versa. 

II. Of the fonrteeii muscles attached to the tibia, 

9 are attached to the upper fifth and move the leg 

upon the thigh and vice-versa. 
5 are attached to the shaft and move the foot on the 

•leg and vice-versa. 

III. Of the nine muscles attached to the fibula, 

1 is attached to the upper end and moves the leg 

upon the thigh and vice-versa. 
8 are attached to the shaft and move the foot upon 

the leg and vice-versa. 

BONES OF THE FOOT. 

The foot is composed of twenty-six bones, and is divided into 
three segments, as follows : 

1st. Tarsus, 7 bones. 
2nd. Metatarsus, 5 bones. 
3rd. Digits (5), 14 bones. 

I. The bones of the tarsus are seven in number, and may be 
enumerated as follows : 

Astragalus, I. 

Calcaneum, I. 

Scaphoid, I. 

Cuneiform, 3. 

Cuboid, 1. 

Total, 7 bones. 

II. The metatarsal bones are five in number and are named 
in numerical order from within outwards, or from the tibial to- 
wards the fibular side of the foot. 



THE BONES 01- THE FOOT. 



157 



III. The digits are also five in number, and each consists of 
three bones, named phalanges, with the exception of the great 
toe or " hallux," which has only two. The phalanges are four- 
teen in number and are counted from behind forwards, or from 
the heel towards the toes. The digits are named numerically 
from within outwards. 

Plan of the Bones of the Foot. 



Phalanges. 



Metatarsus. 



Cuneiform. 




3rd row. 
2nd row. 
1st row. 



= — Hey's operation. 



— Chopart's operation. 



Internal por- 
tion, 16 bones. 



External por- 
tion, 10 bones. 



This diagram of the bones of the foot is intended to illustrate 
the relative position of the bones to each other as well as the 
situation of the various amputations which are performed in this 
region. 

It also illustrates some points of anatomical value, to which 
the attention of the student is not always directed, viz. : 

I. The bones of the foot may be divided into two lateral halves ', 
the external half comprising ten bones, and the internal half com- 
prising sixteen bones. 

II. The bones of the foot are seen, in the second place, to be 
capable of being divided transversely in the following regions : 
I, between each row of the phalanges, 2, at the junction of the 
metatarsal bones with the tarsus, 3, in the middle of the tarsus, 
between the scaphoid and the cuboid bones, in front, and the as- 
tragalus and the os calcis, behind. The operations of Hey and 
Chopart as indicated in the diagram consist therefore of disarticu- 
lating certain bones of the foot from each other. 



158 BONES OF THE LOWER EXTREMITY. 

III. Chopart's operation consists in removing all the bones of 
the foot except two, viz., the os calcis and the astragalus; Hey's, 
in removing all the bones of the foot except those of the tarsus. 

IV. All of the tarsal bones articulate vtitYi four bones with the 
following exception : 

Os calcis, with two bones. 
External Cuneiform, with six bones. 

TARSAL BONES. 
The seven bones entering into the formation of the tarsus 
have been previously enumerated under the description of the 
bones of the foot. Each one, however, presents certain points of 
interest, and each will therefore receive a special description. 

ASTRAGALUS. 

This bone may be recognized by a rounded head, a broad 
articular facet upon its convex surface, and two articular facets, 
separated by a deep groove, upon its concave surface. 

This bone is divisible into six surfaces, a superior, an inferior, 
an external, an internal, an anterior and a posterior. 

It articulates with four bones, viz., the tibia, the fibula, the 
os calcis and the scaphoid. 

OS CALCIS. 

This bone may be distinguished by its large size and oblong 
shape, also by a large and irregular portion which forms the head, 
and which is directed forwards, and by two articular portions 
upon its upper surface, which are separated by a deep groove. 

The os calcis posesses six surfaces, viz., a superior, an inferior, 
an external, and an internal, an anterior and a posterior. 

It articulates with two bones, viz., the astragalus and the cuboid. 

The os calcis affords attachment to eight muscles as follows : 

f To the upper surf ace . . . .{j)\ Extensor brevis digitorum. 

C Abductor pollicis. 
1 To the under surface. . .(4) F'--' brevis digitorum. 



tachment to eight mus- 
cles, as follows : 



Abductor minimi digiti. 
[Flexor accessorius. 

{Gastrocnemius. 
Plantaris. 
Soleus. 



The plantar fascia derives its attachment from the under sur- 
face of this bone. 

SCAPHOID. 
This bone is so called from its resemblance to a boat. It pos- 



TARSAL BONES. I 59 

sesses two surfaces, viz., an anterior and a posterior ; two bor- 
ders a superior and an inferior ; and two extremities — one broad, 
the other pointed and thick. 

The anterior surface is marked by three facets which articu- 
late with the three cuneiform bones. 

The posterior surface is concave to articulate with the head 
of the astragalus. 

On the internal and lower portion of the bone is a projection, 
termed the tubercle of the scaphoid, for the insertion of the tendon 
of the tibialis posticus muscle. 

Externally is sometimes perceived a facet for articulation with 
the cuboid. 

The scaphoid bone articulates with four bones, viz., the astra- 
galus, and the three cuneiform bones. In rare instances, it artic- 
ulates with the cuboid. 

It affords attachment to only one muscle, viz., the tibialis pos- 
ticus muscle. 

CUBOID. 

This bone is so called from its form. It presents three artic- 
ular surfaces, viz., an anterior, a posterior and an internal ; and 
three non-articular snrfaces, viz., a superior, an inferior and an 
external. 

The superior non-articular surface helps to form the dorsum of 
the foot ; the inferior is grooved for the peroneus longus muscle. 

The posterior articular surface joins the os-calcis ; the anterior 
articulates with the fourth and fifth metatarsal bones, while the 
internal articulates with the external cuneiform bone. 

It will thus be perceived that the cuboid bone articulates, 
like most of the tarsal bones, with four bones, viz., the os calcis, 
the external cuneiform and the fourth and fifth metatarsal bones. 

The cuboid affords attachment to one muscle, viz., the flexor 
brevis pollicis. 

CUNEIFORM BONES. 

These three bones are all six-sided and wedged-shaped. They 
each present a dorsal surface, a plantar surface, a posterior surface, 
an anterior surface and two lateral surfaces. 

The posterior surfaces articulate with the scaphoid, the anterior 
surfaces articulate with the metatarsal bones, the lateral surfaces 
articulate with each other, and, in some cases, with other bones, 
viz, the metatarsal bones and the cuboid. 

The dorsal and plantar surfaces of each of the cuneiform bones 
have no special points of interest, save in the internal cuneiform 



x 6o BONES OF THE LOWER EXTREMITY. 

bone. In this bone, the dorsal surface presents a groove for the 
tendon of the tibialis anticus muscle, and, on its plantar surface, 
a tubercle for the insertion for the tibialis posticus muscle. 

The internal and middle cuneiform bones each articulate with 
four bones, but the external cuneiform articulates with six, since 
three metatarsal bones are in contact with it. 

The internal cuneiform affords attachment to two muscles, viz., 
the tibialis anticus and the tibialis posticus. 

The middle cuneiform bone affords attachment to one muscle, 
viz., the flexor brevis pollicis. 

The external cuneiform bone, at its inferior surface, also 
affords attachment to one muscle, viz., the flexor brevis pollicis 
muscle. 

METATARSAL BONES. 

The metatarsal bones are five in number, are long bones, and 
are divisible, therefore, into a shaft and two extremities. 

The shaft of each is prismoidal in form and is compressed from 
side to side. 

The tarsal extremity or base of each bone is square in shape 
and articulates with the tarsal bones and with each other. 

The anterior extremity forms a rounded head, circumscribed 
by a constricted portion called the neck, and articulates with the 
first row of phalanges. 

Peculiarities of the metatarsal bones. 

The frst metatarsal bone is shorter and larger than 
the rest. It forms the inner border of the foot. 

The second metatarsal bone is the longest and the 
largest of the remaining four. At its base it has three 
articular facets, since it joins with three cuneiform 
bones. 

The third metatarsal bone has two facets on 'the 
outer side of its base and is of small size. 

The fourth metatarsal bone is of small size and has 
a single articular facet upon each side of its base. 

The fifth metatarsal bone is recognized by its broad 
base and by the absence of an articular facet on its outer 
side. 



metatarsal bones. 
Plan of the Metatarsal Articulation, 

Cuneiform. 



161 



; M 



Iff- 2?- 




f=^p 



Metatarsal bones. 

In this diagram are represented, the three cuneiform and cuboid 
bones and the five metatarsal bones. 

The lines represent the points of articulation of the second 
and fourth metatarsal bones. 

It will thus be perceived that the first metatarsal bone has 
only one point of articulation with the tarsus, that the second has 
three, that the third has one, that the fourth has two, and that the 
fifth has one. 

A person, jumping and aligJiting upon the toes, has twenty-two 
joints and forty-four articulations to distribute the shock. These 
may be enumerated as follows : 



Metatarsal Articulations, 


8. 


Tarsus (7x4) 




28. . 


Tibia, 




3. 


Fibula, 




2. 


Femur, 




2. 


Os Innominatum, 




1. 




Total 


44. -f- 2 



:22 joints. 

. If concussion is received upon the heel, only six joints and 
twelve articulations distribute the shock. These six joints are 
as follows : 



OS Calcis, 

Astragalus, 

Tibia, 

Fibula, 

Femur, 

Os Innominatum, 



1. 

3. 
3- 
2. 
2. 
1. 



Total 



6 joints. 



It will be seen that the total number of articulations has been 



1 62 BONES OF THE LOWER EXTREMITY. 

divided by two to indicate the actual number of joints, to which 
the shock is carried, since the total number of articulations of 
each bone has been enumerated and thus the actual number of 
joints has been doubled. 

Points of Surgical Interest. 

The following bony points, upon the inner side of the foot, are 
of surgical value, since they afford guides to the various amputa- 
tions in this region. 

1. The tuberosity of the os calcis, at the extremity of 

the heel. 

2. The inner malleolus, in front of the heel and oppo- 

site the ankle joint. 

3. The anterior projection of the os calcis, one inch be- 

low the malleolus. 

4. The tubercle of the scaphoid bone, one inch in front 

of the malleolus. 

5. The internal cuneiform bone, in front of the tubercle 

of the scaphoid. 

6. The projection of the first metatarsal bone, at the 

base of the great toe. 

7. The extremities of the phalanges of the great toe. 
Upon the outer side of the foot, the following bony points are 

perceived, from behind forwards, which possess a surgical im- 
portance. 

1. The external tubercle of the os calcis. 

2. The external malleolus, which descends lower and 

does not extend as far forwards as the inner. 

3. The peroneal tubercle of the os calcis, which lies one 

inch below the malleolus. 

4. The projection of the base of the %th metatarsal bone. 

PHALANGES. 

There are two phalanges in the great toe, and three in the 
other toes, as in the hand. They are long bones, divisible into a 
central portion of the shaft and two extremities. 

The phalanges of the first row are convex, above, concave, 
upon the under surface, and compressed, from side to side. The 
posterior extremity has a single concave articular surface, for the 
head of the metatarsal bone ; and the anterior extremity, a pul- 
ley-like surface, for the second phalanx. 

The second phalanges are short and diminutive, but somewhat 
broader than the first row. 



THE PHALANGES. 1 63 

The third, or ungual phalanges, including the second phalanx 
of the great toe, are flattened, from above downwards, and ex- 
panded laterally, at the base, to articulate with the second row, 
and, at the opposite extremity, to support the nail and the round- 
ed extremity of the toe. 

The first row of phalanges articulates with the metatarsal 
bones and the second phalanges. 

The second row, in the great toe, articulates with the first pha- 
lanx, and, in the other toes, with the first and third phalanges. 

The third row articulates with the second row of phalanges, 
in all the toes but the great toe, where the third phalanx is 

r 
>* 

MUSCLES ATTACHED TO PHALANGES. 

First Row. 

In the great toe, the abductor pollicis, the adductor 
pollicis, the flexor brevis pollicis, the transversus pedis 
and one of the tendons of the extensor brevis digito- 
rum, are inserted. 

In the second toe, the first and second dorsal in- 
terosseous and the first lumbricalis muscles are in- 
serted. 

In the third toe, the third dorsal and first palmar 
interosseous and the second lumbricalis muscle are 
inserted. 

In the fourth toe, the fourth dorsal and second palmar 
interosseous and the third lumbricalis muscles are 
inserted. 

In the fifth toe, the third plantar interosseus, the 
abductor minimi digiti, the flexor minimi digiti, and 
the fourth lumbricalis muscle are inserted. 
Second Row. 

In the great toe, the extensor longus pollicis and the 
flexor longus pollicis are inserted. 

In the other four toes the extensor longus digitorum, 
one slip of the extensor brevis digitorum, except in the 
little toe, and the flexor brevis digitorum muscles are 
inserted. 
Third Row. 

Two slips of the common tendon of the extensor 
longus and the extensor brevis digitorum, and the 
flexor longus digitorum muscles are inserted into each 
phalanx. 



ARTHROLOGY OR SYNDESMOLOGY. 



STRUCTURE OF JOINTS. 167 



ARTHROLOGY OR SYNDESMOLOGY. 

The name articulation, synonymous with joint, is given, in 
descriptive anatomy, to the connection subsisting, in the recent 
skeleton, between any of the denser component parts, whether 
bone or cartilage. 

Articulations or joints may be arranged in three classes, as 
follows : 

( Dentata. 
Suture. < Serrata. 
( Limbosa 
Harmonia. 
Schindylesis. 
Gomphosis. 
II. Amphiarthrosis, synchondrosis, or symphysis, (limited motion.) 

Enarthrosis (ball and socket joint.) 

III. Diarthrosis, (free motion) 3 varieties •{ Ginglymus (hinge joint.) 

Arthrodia (gliding joint.) 



I. Synarthrosis, (immovable) 4 varieties, 



The following structures enter into the formation, to a greater 
or less extent, of all the joints : 

1. Bone, (articular lamella.) 

2. Ligaments. 

3. Cartilage, (articular, costal, or membraniform.) 

4. Fibro-cartilage. 

5. Synovial membrane. 

The LIGAMENTS are usually composed of white fibrous tissue, 
although two ligaments of the body are composed purely of yellow 
elastic tissue. These two ligaments are the ligamentum sub-flava 
and the ligamentum nuchse, both of which are connected with the 
vertebral column. 

Ligaments may be divided into three principal classes: 1st, 
capsular ; 2nd, fascicular ; 3rd, funicular. 

Capsular ligaments (from capsula, a small coffer or box) are 
barrel-shaped expansions, attached by their extremities around 
the margin of the articulating surfaces composing the joint. 

Funicular ligaments (funis, a rope) are those which resemble 
a cord in their appearance. 

Fascicular ligaments (fascis, a bundle) are flattened bands, 
more or less expanded, somewhat like a riband, and comprise the 
remaining varieties. 

CARTILAGE is divided into two varieties, viz., temporary and 
permanent. The latter is divided into (1) articular, (2) costal, (3) 
membra7iiform. 

Articular cartilage is either disposed as a thin layer between 
two articular surfaces, or it forms an encrustation upon the artic- 



1 68 



ARTHROLOGY OR SYNDESMOLOGY. 



ular ends of bones, entering into the composition of diathrodial 
or movable joints. 

Fibro-cartilage may be either circumferential, where it helps to 
deepen cavities ; 2, connective, where it helps to bind parts to- 
gether ; 3., inter-articular, where it tends to separate opposing 
bones, and 4, stratiform, where it lines grooves for tendons. 

The synovial membranes of the joints may be, 1st, articular, 
where they serve simply to lubricate the joint ; 2nd, vesicular, 
where they form shut sacs, called bursse ; 3rd, vaginal, where 
they form a sheath for tendons. 

The following table illustrates by a tree-like figure, the three 
principal divisions of joints and the subdivisions of each. 

It will thus be seen that amp hiar thro sis (joints with limited 
motion) is divided into three distinct types, called respectively, 
synchondrosis, syndesmosis, syssarcosis ; that synarthrosis (im- 
movable articulations) comprises four types, which are respect- 
ively named sutura, harmonia, schindylesis, and gomphosis ; and 
finally, that diarthrosis (joints with" free motion) comprises three 
principal forms, called respectively, arthrbdia, ginglymus, and 
enarthrosis. 

Diagram of the Varieties of Joints. 




Enarthorsis. [ 



ARTHROLOGY. 

Each of these types will be considered in their order. 
Synchondrosis, or symphysis, means union by cartilage. 
Syndesmosis means union by ligament. 
Syssarcosis means union by muscular tissue. 



VA RIE TIES OF AR TIC ULA TIONS. j 69 

Suture means union of bone by a series of processes and 
indentations, which fit into each other. It is often 
divided as follows : 

Sutiira dentata, where the interlocking processes are 
large and extensive, as in the sagittal and lam- 
bdoidal sutures. 
Sutura serrata, where the interlocking processes are 
smaller and more regularly distributed, as in the 
temporary suture of the frontal bone. 
Sutura limbosa, where the articular surfaces are bev- 
elled, and one overlaps the other, as in the fronto- 
parietal suture, 
Harmonia means a mere apposition of two rough bony sur- 
faces, as is found between the two halves of the upper 
jaw and in the temporo-parietal suture. 
Schindylesis means the insertion of a thin plate of bone into a 
cleft, formed by the separation of the two plates of 
another bone, as is perceived in the articulation of the 
rostrum of'the sphenoid bone with the vomer. 
Gomphosis means the implantation of one bone into a process 
of another bone, of- which the teeth, by their insertion 
into the alveolar process of'the jaws, afford examples. 
Enarthrosis means the articulation of a globular head of a 
long bone into a cup-shaped cavity. It is also called 
the ball-and-socket joint, and an example of it is af- 
forded in the articulation of the femur at the hip. 
Arthrodia comprises all articulations of surfaces which are flat 
or nearly so. It admits of only a gliding movement, 
which movement is never extensive. An example of 
this form of articulation is afforded where the acromion 
process of the scapula joins with the clavicle. 
Ginglymus, or hinge-joint, includes all joints which admit of 
either an angular, a lateral, or a rotary motion. By 
some anatqmists, the latter form of articulation is 
called diartlirosis rotatorius. Examples of the gingly- 
mus form of articulation are present in the knee, 
ankle, elbow, in the articulation of the head of the 
radius and the ulna, and in the articulation of the atlas 
with the axis. 
Joints admit of seven varieties of motion, viz. : 

1. Flexion. 

2. Extension. 

3. Adduction, 



1^0 ARTHROLOGY OR SYNDESMOLOGY. 

4. Abduction. 

5. Rotation. 

6. Circumduction. 

7. Gliding movement. 

In the first two of these movements, the hinge and ball-end 
socket joints are most prominently useful. In the next four, the 
ball-and-socket joints are most chiefly used, while, in the latter, 
the arthrodial joints are alone implicated. 

The articular lamella differs from the ordinary bone t/ssue (1) 
in containing no Haversian canals, (2) its lacunae are larger, (3) it 
contains no canaliculi. 

A. 

ARTICULATIONS OF THE CRANIUM WITH THE 

SPINE. 

These include the occipito-atloid, the occipito-axoid, and the 
atlo-axoid articulations. The latter, although not directly affect- 
ing the head, cannot well be separated from this group. 

Occipito-atloid Articulation. 

This joint is a double arthrodia between the condyles of the 
occipital bone and the superior articular surfaces of the atlas. 
Its ligaments are seven in number, as follows : 
Two anterior occipito-atloid. 
A posterior occipito-atloid. 
Two lateral occipito-atloid. 
Two capsular. 
The anterior ligaments are two in number, viz. : the superficial, 
which springs from the basilar process of the occipital 
bone, and is attached to the anterior tubercle of the 
atlas ; and the deep, which extends from the anterior 
margin of the foramen magnum to the upper border 
of the anterior arch of the atlas. 
The posterior ligament extends from the posterior margin of 
the foramen magnum to the upper border of the pos- 
terior arch of the atlas. 

It is perforated by the vertebral arteries and sub- 
occipital nerves. 
The lateral ligaments extend from the jugular processes of the 
occipital bone to the base of each of the transverse 
processes of the atlas. 
The capsular ligaments surround the arthrodial articulations, 
and are lined by a synovial membrane, which often 



AR TTCULA TIONS OF OCCIPITA L BONE. I j \ 

communicates with the synovial membrane between 
the odontoid process and the transverse ligament of 
the atlas. 
The articulation of the condyles of the occipital bone with the 
cups of the atlas, corresponds nearly to a line drawn 
through the anterior margins of the mastoid processes 
of the temporal bone. 

Occipito-axoid Articulation. 
The head and the axis do not touch each other, but neverthe- 
less, the four following connecting ligaments exist : 
Occipito-axoid ligament. 

Three occipito-odontoid ligaments, comprising 
Two lateral or check ligaments. 
A median or suspensory ligament. 
The occipito-axoid ligament is a continuation upwards of the 
posterior common ligament of the bodies of the ver- 
tebrae. 
The check ligaments extend, upon either side, from the inner 
side of the condyles of the occipital bone to the sides 
of the odontoid process of the axis, near to its apex. 
The suspensory ligament extends from the anterior margin of 
the foramen magnum to the apex of the odontoid 
process of the axis. 

Atlo-axoid Articulation. 
This is a complex joint, consisting, first, of a double arthrodia 
between the articular processes of the atlas and the 
axis, and also of a double diarthrosis rotatorius between 
the odontoid process and the atlas. 
Its ligaments are six in number, which are as follows : 
Two anterior atlo-axoid ligaments. 
A posterior atlo-axoid ligament. 
A transverse ligament. 
Two capsular ligaments. 
The a?iterior ligaments consist of a superficial ligament, which 
extends from the anterior tubercle of the atlas to the 
base of the odontoid process and the body of the axis ; 
and a deep ligament which extends from the lower 
border of the anterior arch of the atlas to the base of 
the odontoid process and the body of the axis. 
The posterior ligament extends from the lower border of the 
posterior arch of the atlas to the upper border of the 
laminae of the axis. 



172 ARTHROLOGY OR SYNDESMOLOGY. 

The transverse ligament divides the ring of the atlas into two 
portions, and embraces the neck of the odontoid process 
of the axis. It extends between the tubercles, on the 
inner surface of each of the lateral masses of the atlas. 
This ligament gives off two fasciculi, one of which 
passes vertically upwards, and the other downwards, 
and thus form, with the transverse band, the so-called 
cruciform ligament. 
The capsular ligaments surround the two arthrodial articulations. 
There art four synovial membranes connected with this joint, 
one lining the inner surface of each of the capsular liga- 
ments, one between the anterior surface of the odontoid 
process and the posterior surface of the anterior arch of 
the atlas, and the other between the posterior surface 
of the odontoid process and the transverse ligament 
of the atlas. 

B. 

ARTICULATIONS OF THE VERTEBRAE. 

The vertebrae are joined together by their bodies, their laminae, 
their articular processes, their spinous processes, and their trans- 
verse processes. 

The Bodies are united by three sets of ligaments, viz. : 

I. Intervertebral discs. 

These are lenticular-shaped discs of flbro-cartilage, 
which are firmly adherent to the bodies of the ad- 
joining vertebrae. 

II. The anterior common ligament. 

This ligament joins the bodies of the vertebrae, in 
front, and extends from the axis to the sacrum. It 
is attached also to each of the intervertebral discs 
of flbro-cartilage between the vertebrae. 
III. The posterior common ligament. 

This ligament extends between the posterior sur- 
faces of the bodies of all the vertebrae from the axis 
above to the sacrum below. It is continuous, at its 
upper portion, with the occipito-axoid ligament. 
The ARTICULAR PROCESSES are united by two ligaments called 
the capsular ligaments, which are lined internally by a 
synovial membrane. 
The LAMINAE are joined together by highly elastic bands, one 

on either side, called the ligament a subflava. 
The SPINOUS PROCESSES are joined together by two ligaments. 



ARTICULATIONS OF THE RIBS. 173 

I. The interspinous ligaments. 

These connect the adjacent margins of the adjoin- 
ing spinous processes of the vertebrae. 
II. The supraspinous ligament. 

This ligament extends from the seventh cervical 
vertebrae to the sacrum. It connects the apices of 
the spinous processes of the vertebrae. 
The TRANSVERSE PROCESSES are joined together by ligaments 
called the inter*tra?tsverse ligaments of the vertebral 
column. They are often insignificant or wanting in 
the cervical region, and they are attached to the adja- 
cent margins of the adjoining transverse processes of 
all the vertebrae. 

C. 

ARTICULATIONS OF THE RIBS. 
The ribs have five distinct points of articulation which may be 
enumerated as follows : 

I. Costo-vertebral articulations. 
II. Costo-transverse articulations. 
III. Chondro-sternal articulations. 
IV. Chondro-costal articulations. 
V. Chondro-chondral articulations. 

Costo- Vertebral Articulation. 
These articulations consist of a double arthrodia between the 
heads of each rib and the bodies of two adjoining vertebrae. The 
exceptions to this rule exist in the first, tenth, eleventh, and 
twelfth ribs, which articulate with only one vertebra and there- 
fore form but a single arthrodial joint. The ligaments of these 
articulations are three in number, viz. : 

I. The capsular ligament, which surrounds the articular sur- 
faces. 
II. The anterior costo-vertebral ligament, or stellate ligament. 
consisting of three fasciculi, one joined to the vertebra 
above, another to the vertebra below, and the middle 
one to the intervertebral disc between them. 
III. The inter articular costo-vertebral ligament, which connects 
the head of the rib to an interveterbral disc of fibro- 
cartilage. 

Costo-Transverse Articulation. 
These articulations are ten in number, are arthrodial in char- 
acter, and serve to connect the tubercles of the ten upper ribs and 



174 ARTHROLOGY OR SYNDESMOLOGY. 

the transverse processes of the lower of the two vertebrae, with 
which the head of each rib articulates. The ligaments of these 
joints are three in number, viz. : 

I. The posterior costo-transverse ligament, which extends from 
the apex of the transverse process of the vertebra to 
the outer part of the tubercle of the rib. 
II. The middle costo-transverse ligament, which connects the 
front of the transverse process of the vertebra to the 
posterior portion of the neck of the rib. 

III. The anterior costo-transverse ligament, which connects the 

lower border of the transverse process of that vertebra 
which lies above the rib, to the upper border of the 
neck of the rib below. 

Chondro- Sternal Articulation. 
These articulations are situated between the extremities of 
the costal-cartilages of the seven upper ribs, on either side, and 
the margins of the sternum. The first articulation is a synar- 
throdial joint, since it presents no synovial membrane, while the 
other six are arthrodial in character. The ligaments of these 
articulations are as follows : 

I. The capsular ligament, which blends with the anterior and 
posterior ligaments. 
II. The anierior chondro-sternal ligament, which connects the 
front of the sternum with the front of the costal-car- 
tilage. 
III. The posterior chondro-sternal ligament, which connects 
the back of the sternum to the back of the costal- 
cartilage. 

IV. The chondro- xiphoid ligameiit, which connects the xyphoid 

appendix to the front of the sixth or seventh costal- 
cartilage. 
An inter articular fibro-cartilage exists in the second articula- 
tion only and is attached between the manubrium and the gladi- 
olus, on the one hand, and the tip of the costal-cartilage, on the 
other. 

Chondro-Costal Articulation. 
These articulations exist between the outer extremity of each 
costal-cartilage and the depression on the outer end of the corres- 
ponding rib. These parts are bound together by the blending 
of the periosteum and the perichondrium. 

Chondro-Chondral Articulation. 
These articulations are formed by the joining together of the 



ARTICULATIONS OF THE PELVIS. 



175 



costal-cartilages of the 8th, 9th and 10th rib. A synovial mem- 
brane is wanting in the first and the last of these articulations 
The lieaments of each t>f these joints are two in number, 
viz., a capsular and an intercostal, which bind the cartilages to- 
gether. 

D. 

ARTICULATIONS OF PELVIS. 

The articulations of the pelvis are four in number as follows : 
I. Sacro-iliac articulation. 
II. Pubic articulation. 

III. Sacro-coccygeal articulation. 

IV. Sacro-vertebral articulation. 

Each of these articulations require a separate description. 

Sacro-Iliac Articulation. 
This articulation is one of the synchondroses and presents 
five ligaments as follows : 

I. The anterior sacro-iliac ligament, which connects the an- 
terior surfaces of the sacrum and the ilium. 
II. The posterior sacro-iliac ligament, which connects the 
posterior portion of the lateral surface of the sacrum 
with the inner surface of the projecting portion of the 
ilium. 
III. The oblique sacro-iliac ligament, which connects the 
posterior superior spine of the ilium with the back 
of the third or fourth piece of the sacrum. 

Ligaments between the Sacrum and Ischium. 

The great sacro-sciatic ligament, which arises from the poste- 
rior inferior spine of the ilium, as well as from the posterior sur- 
faces and the margins of the sacrum and the coccyx, and is inserted 
into the inner margin of the tuberosity and the ascending ramus 
of the ischium. 

The lesser sacro-sciatic ligament, which arises from the mar- 
gins of the sacrum and of the coccyx and is inserted into the 
spine of the ischium. 

This ligament separates the greater and the lesser sacro-sciatic 
foramina. 

Pubic Articulation. 

This joint is one of the amphi-arthrodial joints. It posesses 
four ligaments as follows : 

I. The anterior pubic ligament, which connects the front sur- 
faces of the two pubic bones. 



Ij6 ARTHROLOGY OR SYNDESMOLOGY. 

II. The posterior pubic ligament, which connects the posterior 
surfaces of the two pubic bones. 
III. The supra-pubic ligament, which joins the upper border 

of the pubic bones. 
IV. The sub-pubic ligament, which forms a fibrous arch be- 
tween the rami of the pubic bones. 
An i7iter articular fibro-cartilage exists between the bones 
forming this joint. 

Sacrococcygeal Articulation. 
This articulation is similar to those between the bodies of the 
vertebrae. It posesses three ligaments as follows : 

I. The anterior sacro-coccygeal ligament, which connects the 
front of the sacrum to the front of the coccyx. 
II. The posterior sacro-coccygeal ligament, which connects the 
margins of the lower orifice of the sacral canal to the 
back of the coccyx. 
An interarticular fibro-cartilage exists also in this joint. 

Sacro-Vertebral Articulation. 
This articulation is similar to other vertebral articulations ex- 
cept that it has two additional ligaments, viz. : 

I. The lumbosacral ligament (sacro-vertebral), which connects 
the fifth lumbar vertebrae, in front, to the sides of the 
base of the sacrum. 
II. The ilio-lumbar ligament (lumbo-iliac), which connects the 
tip of the transverse process of the fifth lumbar verte- 
brae to the crest of the ilium. 

E. 

TEMPORO-MAXILLARY ARTICULATION. 

This joint is a double arthrodial articulation, existing between 
the condyles of the lower jaw, on the one hand, and the anterior 
part of each glenoid cavity, on the other. 

It has two synovial membranes, which are separated by 
an interarticular fibro-cartilage, and which occasionally com- 
municate. 

It has four ligaments, which are as follows : 

I. The capsular ligament, which connects the circumfer- 
ence of the glenoid cavity of the temporal bone 
and the eminentia articularis, with the neck of the 
condyle of the jaw. 
II. The external lateral ligament, which connects the 



JOINTS OF UPPER EXTREMITY. \yj 

outer surface and the tubercle of the zygoma with 
the outer surface and the posterior border of the 
neck of the condyle of the lower jaw. 

III. The internal lateral ligament, which connects the 

spinous process of the sphenoid bone to the inner 
margin of the dental foramen. This ligament 
bears a close relation to the internal maxillary 
artery and the inferior dental vessels and nerve. 

IV. The stylo-maxillary ligament, which connects the 

apex of the styloid process of the temporal bone 
to the angle and the posterior border of the ramus 
of the jaw. It separates the parotid gland from 
the submaxillary gland. 

F. 

ARTICULATIONS OF THE UPPER EXTREMITY. 

The articulations of the upper extremity may be arranged 
in the following groups : 

I. Sterno-clavicular articulation. 
II. Scapuloclavicular articulation. 

III. Ligaments of the scapula. 

IV. Shoulder joint. 
V. Elbow joint. 

VI. Radio-ulnar articulations. 
VII. Wrist joint. 
VIII. Articulation of the carpal bones. 
IX. Carpo-metacarpal articulations. 

X. Metacarpophalangeal articulations. 
XL Articulations of the phalanges. 

Sterno-clavicular Articulation. 

This joint is formed by the articulation of the sternum with 
the inner extremity of the clavicle. It has two synovial mem- 
branes, which are situated on either side of an interarticular fibro- 
cartilage. These two sacs occasionally communicate through an 
orifice produced by perforation of this cartilage, at its centre. Its 
ligaments are five in number, as follows : 

I. The anterior sterno-clavicular ligament, which connects the 

front of the clavicle to the first piece of the sternum. 
II. The posterior sterno-clavicular ligament, which connects 
the back part of the clavicle to the first piece of the 
sternum. 



178 ARTHROLOGY OR SYNDESMOLOGY. 

III. The interclavicular ligament, which connects the inner 

extremities of both clavicles with the margin of the 
sternum and with each other. 

IV. The costoclavicular, or rhomboid ligament, which connects 

the under surface of the clavicle to the cartilage of the 
first rib. 

V. The capsular ligament, which extends from the circumfer- 

ence of the head of the clavicle to the sternum. 

The inter articular fibro-cartilage, present between the bones 
of this joint, moves freely with the clavicle. This joint admits 
of slight movements in almost every direction. 

The ster no-clavicular articulation is an important surgical local- 
ity, since the innominate artery and the points of origin of the 
subclavian and the carotid arteries, upon the right side, and the 
common carotid artery, upon the left side, are in close relation. 
The innominate vein, upon the left side, and the apices of the lungs, 
upon both sides, are also present in this region. 

Acromioclavicular Articulation. 

This is an arthrodial joint and possesses five ligaments, which 
are as follows : 

I. The superior acromio-clavicular ligament, which extends 

from the upper part of the outer end of the clavicle 
to the upper surface of the acromion process of the 
scapula. 

II. The inferior acromio-clavicular ligament, which connects 

the under surface of the outer end of the clavicle to 
the under surface of the acromion process of the 
scapula. 

III. The trapezoid ligament, which connects the upper surface 

of the coracoid process of the scapula to the under 
surface of the clavicle. This ligament is sometimes 
described as one fasciculus of the coraco-clavicular 
ligament, of which the conoid ligament forms the 
remainder. 

IV. The conoid ligament, which connects the base of the cora- 

coid process of the scapula to the conoid tubercle of 
the clavicle. 
An interarticular fibro cartilage is present between the bones 
which form this joint, and is attached to the superior acromio- 
clavicular ligament. 

This joint has usually but one synovial membrane. The con- 
oid and trapezoid ligaments are not properly those of a joint, but 



THE SHOULDER JOINT. 179 

are usually described in connection with the acromioclavicular 
articulation. 

Ligaments of the Scapula. 
The scapula has connected with it two ligaments, which do 
not properly belong to any joint, but which are usually described 
in connection with the acromio-clavicular articulation. These 
two ligaments are as follows : 

I. The anterior or coraco-acromial ligament. 

This ligament connects the acromion process of the 
scapula with the outer border of the coracoid process, 
and thus completes the vault above the head of the 
humerus. 
II. The transverse or supra-scapular ligament. 

This ligament extends from the base of the coracoid 
process to the inner margin of the supra-scapular 
notch. It converts this portion of the bone into a 
foramen, which transmits the supra-scapular nerve. 

Shoulder-Joint. 

This is an enathrodial joint and is formed by the globular head 
of the humerus and the glenoid cavity of the scapula. It possesses 
three ligaments which are as follows : 

I. The capsular ligament, which connects the neck of the 
scapula, at the margin of its glenoid cavity, to the 
anatomical neck of the humerus. 
II. The coraco-humeral ligament, which connects the coracoid 
process of the scapula with the anterior part of the 
greater tuberosity of the humerus. It is intimately 
blended with the capsular ligament. 
. III. The glenoid ligament, which is a fibro-cartilaginous ring, 
triangular on section, attached to the circumference 
of the glenoid cavity. It is continuous, above, with 
the tendon of the long head of the biceps muscle. 
The synovial membrane of the shoulder-joint is prolonged, as a 
sheath, upon the tendon of the biceps, the tendon of the subscap- 
laris, and the tendon of the infra-spinatus muscles. It communi- 
cates with a bursa beneath both the infra-spinatus and the sub- 
scapulars muscles. A bursa between the upper part of the cap- 
sular ligament and the deltoid muscle also exists, but it does not 
communicate with the synovial membrane of the shoulder joint. 
The capsular ligament is remarkably loose and is attached 
around the glenoid cavity outside of the glenoid ligament, and to 
the humerus, where the neck springs from the tuberosities and the 



■l8o ARTHROLOGY OR SYNDE5M0L0GY. 

shaft. This ligament possesses three openings, through which 
the prolongations of the synovial membrane upon the tendons of 
the above named muscles take place. 

The vessels of this joint are derived from the circumflex and 
the supra-scapular arteries. 

The nerves of the shoulder-joint are derived from the circum- 
flex and the supra-scapular trunks. 

The movements of the shoulder-joint are very free arid embrace 
all the varieties possible to joints. 

The Elbow Joint. 

This is a ginglymus articulation between the lower end of 
the humerus and the greater sigmoid cavity of the ulna and the 
head of the radius. 

It has four ligaments, as follows : 
I. The anterior ligame7it, which connects the inner condyle 
and the anterior portion of the humerus, with the 
orbicular ligament of the radius and with the under 
surface of the coronoid process of the ulna. 
II. The posterior ligament, which connects the apex and sides 
of the olecranon process of the ulna, to the lower end 
of the posterior surface of the humerus, above the 
margin of the olecranon fossa. 

III. The external lateral ligament, which connects the external 

condyle of the humerus with the orbicular ligament 
of the radius. 

IV. The internal lateral ligament, which connects the internal 

condyle of the humerus with the inner border of the 
coronoid and olecranon processes of the ulna. 

The synovial membrane of this joint lines the coronoid and the 
olecranon fossae of the humerus and also dips down between the 
articular surface of the superior radio-ulnar articulation. It is also 
reflected over the anterior, posterior, and lateral ligaments of the 
joint. 

The vessels of this joint are derived from the superior and 
inferior profunda, the anastomotica magna, and the radial, ulnar, 
and interosseous recurrent arteries. 

The nerves to this joint are derived from the ulnar and the 
musculo-cutaneous nerve. 

The movements of the elbow joint consist of flexion and ex- 
tension only, although, from the direction of the articulating sur- 
faces of the humerus, the hand during flexion moves in a plane 
internal to the direction of the axis of the shaft of the humerus. 



articulation of radius and ulna. \%\ 

Radio-Ulnar Articulations. 
The bones of the forearm are connected together at their 
upper extremities, their shafts, and their lower extremities. Thus 
three articulations are formed, called the superior, the middle 
and the inferior. 
Superior articulation. 

This is a lateral ginglymus joint between the circumference 
of the head of the radius and the lesser sigmoid cavity of the ulna. 
The opposing surfaces of bone are covered with cartilage and a 
synovia] membrane is interposed between them, which is continu- 
ous with that of the elbow joint. Its only ligament is called the 
annular or orbicular ligament. 

The orbicular ligament is a strong flattened band of 
fibrous tissue, which forms four-fifths of the circumfer- 
ence of a circle and which surrounds the upper part 
of the neck of the radius. It is attached to the 
anterior and the posterior margins of the lesser sig- 
moid cavity of the ulna. 

The inner surface of this ligament is lined with a 
synovial membrane, while the outer surface affords 
attachment for the external lateral ligament of the 
elbow joint. 
Middle articulation. 

The shafts of the ulna and the radius are joined, at their con- 
tiguous borders, by two ligaments, as follows : 

The oblique or round ligament, which is a narrow 
fasciculus extending downwards and outwards from 
the tubercle, at the base of the coronoid process of the 
ulna, to the shaft of the radius, one half inch below its 
tubercle. 

The interosseous ligament, which is a broad and 
thin plane of aponeurotic fibres, extending, obliquely 
downwards and inwards, from the interosseous ridge 
on the radius to that of the ulna. It is deficient, 
above, commencing about one inch below the tubercle 
of the radius ; is broader in its middle portion than at 
either extremity ; and, through the space left by its 
deficiency above, the posterior interosseous vessels pass. 
Inferior articulation. 

This is a lateral ginglymus joint formed by the head of the 
ulna and the sigmoid cavity of the radius. These surfaces are 
covered with cartilage and are connected together by the following 
ligaments. 



1 82 ARTHROLOGY OR SYNDESMOLOGY. 

1, The anterior radio-ulnar ligament, which connects 
the anterior margin of the sigmoid cavity of the radius 
to the anterior portion of the head of the ulna. 

2. The posterior radio-ulnar ligament, which connects 
the posterior margin of the sigmoid cavity to the pos- 
terior portion of the head of the ulna. 

A triangular fibro-cartilage also extends from the lower mar- 
gin of the sigmoid cavity to* the depression at the root of the 
styloid process of the ulna. This cartilage is lined, both upon 
its upper and lower surfaces, by synovial membrane, derived re- 
spectively from the radio-ulnar and the radio-carpal articulations, 
and is blended, at its margins, with the other ligaments of the joint. 

The synovial membrane of this joint is very largely developed 
and is termed the membrana sacciformis. It occasionally com- 
municates with the synovial membrane of the wrist joint through 
an opening in the centre of the triangular fibro-cartilage. 

The Wrist Joint. 

This articulation is regarded by some as an enarthrodial, and 
by others as an ar thro dial joint. It is formed by three of the 
upper row of carpal bones, viz., the scaphoid, the semilunar and 
the cuneiform, and by the lower surface of the radius and the trian- 
gular fibro-cartilage of the inferior radio-ulnar articulation. The 
ligaments of this joint are four in number and may be enumerated 
as follows : 

I. The external lateral ligament (radio-carpal), which connects 
the apex of the styloid process of the radius to the 
scaphoid, the trapezium, and the anterior annular liga- 
ment of carpus. 
II. The internal lateral ligament (ulno-carpal), which connects 
the apex of the styloid process of the ulna with the 
cuneiform and the pisiform bones, and with the anterior 
annular ligament of the carpus. 

III. The ayiterior ligament, which connects the head of the 

ulna and the anterior margin of the radius and its 
styloid process, with the scaphoid, semilunar, and 
cuneiform bones. 

It is occasionally attached to the os magnum. 

IV. The posterior ligament, which connects the posterior 

margin of the radius with the scaphoid, semilunar and 
cuneiform bones. 
The vessels of the wrist joint are the anterior and posterior 
carpal branches of both the radial and the ulnar arteries, tht: 



JOIN TS OF THE' CA RP US. 1 8 3 

anterior and posterior interosseous arteries, and the ascending 
branches of the deep palmar arch. 

The nervous supply of the wrist joint is derived from the ulnar 
nerve. 

The wrist joint admits of all possible movements but that of 
rotation. 

The wrist joint is opened by inserting a knife, with its edge 
directed upwards and inwards, at the apex of the styloid process 
of the ulna. 

Articulations of the Carpus. 

Articulations of the bones of the proximal row. 

The first three bones of the carpus, viz., the scaphoid, the 
semilunar, and the cuneiform, are joined together by two arthrod- 
ial articulations. 

The ligaments of these articulations consist of two dorsal, two 
palmar, and two interosseous ligaments. 

The pisiform bone is joined to the cuneiform by a separate 
ar thro dial joint, having a separate synovial membrane. 

The two ligaments of this joint connect the pisiform bone to 
the unciform bone and also to the base of the 5th metacarpal 
bone. 

Articulation of the bones of the distal row. 

The four bones comprising the second row of the carpus are 
joined together by three arthrodial articulations. 

The ligaments of these three articulations are three dorsal; 
three palmar and three interosseous ligaments. 

Articulation of the two rows of carpal bones. 

Upon each side of the wrist, two arthrodial articulations exist 
between the two rows of the carpus, and, in the centre, a variety 
of enarthrodial articulation is formed between the os magnum 
and the unciform bone above, and the scaphoid, semilunar, and 
cuneiform bones below. 

The inner arthrodial joint exists between the cuneiform and 
the unciform bone, while the outer is formed between the scaphoid 
bone, above, and the trapezium and trapezoid bones, below. 

The ligaments which unite the two rows of carpal bones con- 
sist of a dorsal, a palmar, and two lateral ligaments. The two 
lateral ligaments are continuous with the lateral ligaments of the 
wrist joint. 



1 84 ARTHROLOGY OR SYNDESMOLOGY. 

The synovial membranes of the carpus are five in number, and 
are situated as follows : 

f Lower end of the ulna. 
The first (membrana sacciformis) lines the] Sigmoid cavity of the radius. 

following parts : 1 Upper surface of the triangular inter- 
im articular fibro-cartilage. 

(Above \ Lower end of radius. 
' ] Interarticular fibro-cartilage. 
( Scaphoid. 
Below. ■< Semilunar. 
( Cuneiform bones, 
f The contiguous surfaces of the proxim- 
al and distal rows of carpal bones. 
The third is very extensive and lines the fol- \ The contiguous surfaces of the distal 

lowing parts | row of carpal bones. 

I The carpal extremities of the inner four 
|^ metacarpal bones, 

The fourth is situated between the trapezium and the metacarpal bones of the thumb. 
The fifth is situated between the cuneiform and the pisiform bones. 

The furrow between the thick skin of the palm and the skin 
of the forearm, on the anterior surface of the wrist, is a guide to 
the upper border of the annular ligament and the articulation be- 
tween the first and second rows of the carpus. 

Carpometacarpal Articulations. 

The trapezium and the metacarpal bone of the thumb are 
united by a capsular ligament and are lined by a separate synovial 
membrane. 

The four inner metacarpal bones unite with the carpus by four 
arthrodial joints, which are formed as follows: 

2nd. Metacarpal bone and trapezium, trapezoid, os magnum. 

3rd. Metacarpal bone and os magnum. 

4th. Metacarpal bone and os magnum and unciform. 

5th. Metacarpal bone and unciform. 

The ligaments of these joints are called the dorsal, the palmar, 

and the interosseous ligaments. 
The dorsal ligaments are two in number to each metacarpal 
bone, with the exception of the fifth, which has but 
one. 
The palmar ligaments are three in number and are connected 

with the third metacarpal bones. 
The interosseous ligame?its connect the third and fourth meta- 
carpal bones to the os magnum and the unciform 
bones. 

Metacarpo-Metacarpal Articulations, 
The metacarpal bone of the thumb is not connected to the 
other bones of the metacarpus. 



METACARPAL JOINTS. 1 85 

The four inner metacarpal bones are connected to each other 

both at their carpal and at their digital extremities. 
Carpal extremities. 

The articulations of the carpal extremities of the 
metacarpal bones are three in number and are arthrod- 
ial in character. 

The ligaments of these joints consist first, of an 
interosseous set, which pass between the bones ; second, 
a dorsal set, which are mainly directed across the back 
of the hand, and third, a palmar set, which is directed 
also transversely across the palm of the hand. 
Digital extremities. 

The digital extremities of the metacarpal bones are 
ail joined together by the so called transverse ligament 
of the metacarpus. 
The tra?isverse ligament of the metacarpus prevents the wide 
separation of the fingers. It can be felt in the interdigital folds 
of the hand, and the skin which covers them is much thinner on 
the dorsal surface of the hand than on the palmar surface. Ab- 
scesses of the palm, for that reason, often open on the back of 
the hand. 

Metacarpophalangeal Articulations. 

The articulations between the metacarpal bones and the cor- 
responding phalanges are ginglymus in variety. 

The ligaments which enter into the formation of these joints 
are as follows : 

I. Ajiterior ox glenoid ligaments. 

These ligaments are lined with a synovial membrane. 
They are grooved for the passage of the flexor tendons 
of the fingers, and, upon either side, they become 
continuous with the sheaths of these tendons. 
II. Lateral ligaments. 

These ligaments connect the tubercles on the sides 
of the head of each metacarpal bone with the glenoid 
ligament, and also with the sides of the first phalanges. 

Phalangeal Articulations. 

The articulations between the rows of phalanges are gingly- 
mus in variety. 

The ligaments of each of these joints, like those of the preced- 
ing articulations, consist of an anterior and two lateral ligaments 
for each joint. 



1 86 arthrology or syndesmology. 

Points of Surgical Interest. 

The three rows of projections, known as " the knuckles '' are 
formed by the proximal bones of the respective joints and may 
serve as guides to amputation, if the fact that the joints lie in 
front of the line of the knuckles be remembered. 

The tendons of the fingers are more closely bound to the 
phalanges between t 'lie joints, than over them, and incisions made 
to relieve suppuration in the region of these tendons should 
therefore be made in the region of the shaft of the phalanges 
rather than near to their articular extremities. 

The furrows which cross the fingers on their palmar surface 
are three in number. The set, nearest to the palm, do not cor- 
respond to the joints between the bones underneath, but the 
seco?id and third sets of furrows are guides to the articulations 
between the phalanges. 

In opening the joint between the trapezium and the metacar- 
pal bone of the tJiumb, the knife should be introduced between 
the ist and 2d metacarpal bones at their angle, with the edge 
directed outwards. 

G. 

ARTICULATIONS OF THE LOWER EXTREMITY. 

The articulations of the lower extremity comprise the follow- 
ing groups : 

I. The hip joint. 
II. The knee joint. 

III. The articulations between the tibia and fibula. 

IV. The ankle joint. 

V. The articulations of the tarsus. 

VI. The tarso-metatarsal articulations. 

VII. The metatarso-phalangeal articulations. 

VIII. The articulations of the phalanges. 

The Coxo-femoral or Hip Joint. 

This articulation is the typical enarthrodial joint of the body. 
It is formed by the reception of the globular head of the femur 
into the acetabulum or cotyloid cavity of the os innominatum. 

The ligaments of this joint are five in number, and may be 
divided into two sets, namely : ist, the circumferential set, and 
2nd, the connecting. The former of these includes two and the 
latter the remaining three of the five ligaments of the hip, as is 
shown below. 



THE HIP-JOINT. jSy 

Circumferential, (2 ligaments.) j j^s verse. 

( Capsular. 
Connecting, (3 ligaments.) < Uio-femoral. 

( Round orligamentum teres. 

The cotyloid ligament of the hip joint is an incomplete fibro- 
cartilaginous ring, which is triangular in section, and 
which is attached, by its base, to the margin of the 
acetabulum. 

It is deficient at the cotyloid notch and its sharp 
free edge closely embraces the head of the femur. Its 
function is to deepen and to alter the shape of the 
bony cavity of the acetabulum. 

The transverse ligament of the hip is a continuation of the 
cotyloid ligament, which extends from one side of the 
cotyloid notch to the other, and thus transforms it into 
a complete foramen. 

The capsular ligament of the hip arises from the margin of 
the acetabulum, from the transverse ligament, and, by 
a few fibres, from the edge of the obturator foramen, 
and is inserted into the base of the neck of the femur, 
above ; in front, into the anterior intertrochanteric 
line ; and, behind, into the posterior intertrochanteric 
line of the femur. 

The capsule of the hip joint has three accessories, viz., the 
ilio-femoral or Y ligament, the ischio-femoral ligament 
and the pubo-femoral ligament. These three accessory 
ligaments are all continuous with the fibres of the cap- 
sular ligament and limit the motions of the joint in 
certain directions. 

The ilio-femoral or accessory ligament arises at the anterior 
- inferior spine of the ilium, and is inserted into the 
lower part of the anterior intertrochanteric line. The 
lower portion of this ligament is bifurcated, and the two 
forks are called, respectively, the inner and the outer. 
This ligament is sometimes called the " Y ligament " 
of the hip joint, as it somewhat resembles that letter 
in shape. It is of great surgical importance, since it 
materially aids in reduction of dislocations at the hip- 
joint by movements of the femur. 

The round ligament or ligamentum teres of the hip joint 
arises from a depression in the head oi the femur in its 
posterior and inferior quadrant, and is inserted, by two 



1 88 ARTHROLOGY OR SYNDESMOLOGY. 

fasciculi, into the margins of the cotyloid notch of the 
acetabulum. 

The SYNOVIAL MEMBRANE of the hip joint embraces the 
greater part not only of the head, but also of the neck of the 
femur, and it invests the capsular ligament, the cotyloid ligament, 
the ligamentum teres and the cavity of the acetabulum. 

It communicates often, through a small opening in the capsu- 
lar ligament of the hip joint, with a bursa situated beneath the 
psoas and the iliacus muscles. 

The vessels of the hip joint are derived from the obturator, the 
accessory obturator, the sciatic, and the internal circumflex arteries. 

The nerves of the hip joint are derived from the great sciatic, 
the obturator, the accessory obturator, and branches from the 
sacral plexus of nerves. 

Movements of the Hip Joint. 

The movements of the hip joint comprise those of flexion, ex- 
tension, adduction, abduction, rotation and circumduction. Of 
these motions, flexion is freer than extension ; of the lateral move- 
ments, abduction is the freest, unless flexion be combined with 
adduction so that one limb passes in front of the other ; while 
circumduction is much less free in the hip than in the shoulder. 

Flexion at the hip joint is checked by the approximation of 
the soft parts and by the ischio-femoral ligament. 

Extension at the hip joint is checked by the ilio-femoral liga- 
ment. This movement of the hip is confined to a few degrees 
only from the line of a perpendicular, in the erect attitude, if the 
pelvis be prevented from participating in the movement and thus 
affording an apparent and not a real movement within the joint. 

Abduction at the hip joint is checked by the Y or ilio-femoral 
ligament and is limited to an arc of less than 90 degrees, if the 
pelvis be prevented from participating in the movement. 

Adduction at the hip joint is checked by the inner fork of the 
Y or ilio-femoral ligament, except when the thigh is flexed and 
that ligament is thus relaxed, when the ischio-femoral ligament 
assists in limiting this movement of the femur. 

Rotation outwards of the femur at the hip joint is checked by 
the ligamentum teres and by the outer fork of the Y or ilio-femoral 
ligament. 

Rotation inwards of the femur at the hip joint is checked by 
the ischio-femoral ligament. 

The entire arc of rotation, which the femur is capable of per- 
forming, is about one-quarter of a circle or 90 degrees. 



THE HIP- JOINT. 189 



Points of Surgical Value Pertaining to the Hir 

The hip-joint is so constructed that atmospheric pressure 
alone will support the weight of the limb, even after all the soft 
parts around the joint have been divided. If air be allowed, how- 
ever, to enter into the joint, by perforation of the acetabulum from 
within the pelvis, the limb will immediately drop. 

The anterior superior spine of the ilium is a valuable aid in 
recognizing the nature of injuries of the hip joint, since the rela- 
tion of the trochanter of the femur to this point is altered in dis- 
location and fracture of that bone. 

A valuable guide to amputation at the hip joint is afforded by 
a furrow, which runs, from the angle between the scrotum and 
the thigh, outwards towards the anterior superior spine of the 
ilium. This furrow lies directly over the capsule of the joint, and 
when fluid is present within the joint, this furrow is obliterated 
and a prominence is often present. 

The great trochanter of the femur is a most important guide 
to the diagnosis of diseased conditions and injuries of the hip- 
joint. Its upper border is situated, when normally placed, on a 
level with the spine of the pub >es and about three-quarters of an 
inch lower than the articular head of the femur. It is superficially 
placed, and is separated from the integument only by the fascia 
of the gluteus maximus muscle and a bursa which lies beneath it. 

Nelaton s guide, to detect any displacement of the femur at 
the hip joint, consists of a line drawn from the anterior superior 
spine, of the ilium to the most prominent part of the tuberosity 
of the ischium. This line should cross the upper border of the 
trochanter of the femur, and it also crosses the centre of the 
cavity of the acetabulum. To properly apply this test, the thigh 
should be semi-flexed and slightly adducted. 

In performing reduction of the dislocations of the femur at 
the hip joint by motion, a valuable guide is afforded to the inex- 
perienced surgeon as to the direction of the head of the femur 
during the various movements required, by remembering that the 
head of the femur will look in the same general direction as does 
the inner surface of the internal condyle of that bone. 

The For ilio-femoral ligament is a most important factor in 
the reduction of dislocations of femur at the hip joint by motion, 
since it affords a point of resistance to the steps of abduction, 
rotation and extension, which are required to accomplish the 
reduction of that bone. 



190 



ARTHROLOGY OR SYNDESMOLOGY. 



THE KNEE JOINT. 

The femoro-tibial articulation or knee joint, is a ginglymus or 
hinge-joint. 

Three bones enter into its formation, namely, the lower articu- 
lar surfaces of the femur, the upper articular surfaces of the tibia, 
and the posterior surface of the patella. 

The ligaments may be divided into two sets, as follows: 
1st. A peripheral or external set. (Extra capsular.) 
2nd. A deep or internal set. (Intra capsular.) 
Under the peripheral or external set are embraced the follow- 
ing ligaments : 

The anterior ligament. 
■ The posterior ligament. 
The internal lateral ligament. 
The external lateral ligament. 
The capsular ligament. 
Under the deep or internal set the following ligaments are 
included : 

The internal semilunar fibro-cartilage. 
The external semilunar fibro-cartilage. 
The transverse ligament. 
The anterior crucial ligament. 
The posterior crucial ligament. 
By some anatomists, two more ligaments called the ligamentum 
mucosum and the ligament a alaria, are described as belonging to 
the internal set, but they have been here excluded, since they are 
more properly considered as reflections of the synovial membranes 
of the joint. 

The anterior ligament, or ligamentum patellce, is a continua- 
tion of the tendon of the rectus femoris muscle. It 
extends from the apex of the patella to the lower part 
of the tubercle of the tibia. It is separated from the 
synovial membrane of the knee joint by a mass of 
adipose tissue, and from the upper part of the tibia by 
a small bursa. 
The posterior ligament of the knee joint, called the ligamentum 
posticum Winslowii is partly derived from, and strength- 
ened by, the tendon of the semimembranosus muscle, 
It extends from the inner tuberosity of the tibia to 
the upper and back part of the outer condyle of the 
femur. 

Cruveilhier describes two additional lateral portions 
of this ligament, closely connected with the tendons 



THE KNEE JOINT. igi 

of the muscles of the calf, and formed chiefly of verti- 
cal fibres, but they are looked upon by many as a part 
of the capsular ligament. 

The internal lateral ligament of the knee connects the inner 
tuberosity of the femur with the inner tuberosity and 
the upper part of the inner surface of the shaft of the 
tibia. It is very broad and is equal in strength to the 
two ligaments in the opposite side of the joint. 

The external lateral ligament of the knee joint consists of two 
portions, a long and a short portion. The long por- 
tion connects the outer tuberosity of the femur to the 
outer part of the head of the fibula ; while the short 
portion connects the outer tuberosity of the femur 
with the apex of the styloid process of the fibula. 

The capsular ligament of the knee joint lies beneath the other 
ligaments above mentioned, and in close relation with 
the synovial membrane of the joint. It is attached, 
above, to the lower end of the femur, just above its ar- 
ticular surface ; in front, to the upper border and the 
sides of the patella ; and, below, to the margins of the 
*head of the tibia and to the semilunar fibro-cartilages 
of the knee-joint. It is an incomplete investment of 
the joint, since it is present only where deficiencies 
exist between the other extrinsic ligaments. 

The internal semilunar fibro-cartilage covers the corresponding 
articular surface of the upper end of the tibia. It is 
narrower and longer than the external. Its convex 
border is blended with the capsular ligament of the 
knee-joint. 

The external semilunar fibro-cartilage covers the external 
articular surface of the end of the tibia. Its anterior 
extremity is blended with the anterior crucial ligament, 
while its posterior extremity is blended with the pos- 
terior crucial ligament. 

The two semilunar fibro-cartilages of the knee serve 
to increase the extent and the depth of the tibial sockets 
and also to modify their form to a perfect adaptation 
to the curves of the femoral condyles, during flexion 
and extension of the joint. 

The transverse ligament of the knee-joint is a small slip of 
fibres which connects, transversely, the two semilunar 
cartilages and which is situated near to their anterior 
extremities. 



I92 ARTHROLOGY OR SYNDESMOLOGY. 

The anterior crucial ligament of the knee-joint arises from the 
tibia, between the anterior extremities of both semi- 
lunar fibro-cartilages, and is inserted into the inner 
and back part of the outer condyle of the femur. 
The posterior crucial ligament of the knee-joint is directed 
nearly vertically from a point of the tibia, between the 
posterior extremities of both semilunar fibro-cartilages, 
to the anterior and outer part of the inner condyle of the 
femur and to the front of the inter-condyloid notch. 

The two crucial ligaments prevent the sliding of the 

tibia upon the femur in a forward or backward direction. 

The synovial membrane of the knee-joint is the largest in the 

body. In its reflections, it forms the following parts which deserve 

attention. 

1. A cul-de-sac, which extends upwards beneath the 
extensor muscles of the thigh for an inch or two above 
the articular surface of the femur. This cul-de-sac is 
supported, during the movements of the joint, by the 
subcrureus muscle, which is inserted into it. 

It is sometimes replaced by a bursa, which, however, 
usually communicates with the knee-joint. 

2. On each side of the patella, it forms a pouch 
beneath the aponeuroses of the vasti muscles, which 
pouch invests the corresponding condyle of the femur. 

3. At the lozver border of the patella, it gives off a 
process called the ligamentum mucosum which is 
attached, in front, to the inter-condyloid notch of the 
femur ; and two other processes, called the ligame?tta 
alaria, which pass obliquely from the sides of the liga- 
mentum mucosum and which fit into the space between 
the tibia, patella and femur. 

The ligamentum mucosum tends to support <the 
synovial membrane of the joint, when both the flexor 
and extensor muscles are relaxed during the erect 
attitude, as when the body leans against some external 
object. 

4. It invests the semilunar fibro-cartilages, except at 
their convex and attached margins, and also surrounds 
the crucial ligaments except at their posterior portion. 

5. It extends beneath the capsular ligament under 
the heads of the gastrocnemius muscle, and is prolong- 
ed, through an opening in the capsular ligament of the 
joint, beneath the tendon of the popliteus muscle. 



THE KNEE-JOINT. 193 

6. Occasionally, it is found to be continued into the 
superior tibio-fibular articulation. 
The vessels of the knee-joint are derived from the five articular 
branches of the popliteal artery, from the anastomotica magna, 
and from the recurrent branch of the tibial artery. 

The nerves are derived from the anterior crural, the obtura- 
tor, the internal popliteal, and the external popliteal nerves. 

Points of Surgical Interest Pertaining to the Knee. 

The tubercle upon the outer side of the head of the tibia has a 
surgical value, since it indicates the level to which the condyles of 
the femur descend and the lowest limit of the synovial membrane 
of the knee-joint. 

In operations in the vicinity of the lower end of the femur, the 
knee should be flexed, in order to draw downwards the cul-de-sac 
of the synovial membrane of the joint which lies beneath the 
tendon of the quadriceps extensor muscle. 

Deviations of the ligamentum patellae from the perpendicular 
line indicate some displacement of that bone. 

The patella lies almost entirely above the condyles of the femur, 
when the knee-joint is extended, and, during flexion of that joint, 
it lies in the inter-condyloid fossa and more upon the external 
condyle than upon the inner. In the act of kneeling the patella 
protects the knee-joint. 

A large deposit of fat beneath the ligamentum patellae is pro- 
vided as a means of packing all vacancies which exist between 
the bones, during the various movements of the joint. This de- 
posit of fat, when the knee is extended, protrudes upon either 
side of the patella and often gives an apparent sense of fluctuation, 
which might lead to a suspicion of fluid within the joint. 

In the region of the ligamentum patellae, there exist three 
bursce ; one deep bursa, under the ligament and separating it from 
the tibia ; and two between it and the integument, the upper of 
which when enlarged creates a swelling called the house-maid's 
knee. 

The bony projection on the inner side of the lower extremity of 
the femur, for the attachment of the fibres of the adductor magnus 
muscle, corresponds to the level of the upper part of the trochlea ; 
a point useful in excision of the knee-joint. 

The movement of outward rotation at the knee-joint is 
checked by the lateral and the crucial ligaments, and is affected 
by the degree of flexion of the joint which, at the same time, 
exists. 



i 9 4 



ARTHROLOGY OR SYNDESMOLOGY. 



A swelling in the popliteal space, often as large as a hen's egg, 
is produced by the enlargement of the popliteal bursa. As this 
bursa not infrequently communicates with the synovial membrane 
of the knee-joint, surgical interference is not without danger. 

Tibio-Fibular Articulations. 

The tibia articulates with the fibula at its superior, its middle, 
and its inferior portions. 
Superior articulation. 

This is an arthrodial joint, whose synovial membrane is 
sometimes continuous with that of the knee. 
Its ligaments are two in number, as follows : 

1. The anterior superior tibio- fibular ligament, which 
connects the front of the head of the fibula with the 
outer tuberosity of the tibia. It consists of two or three 
broad and flat bands, which pass obliquely upwards and 
inwards. 

2. The posterior superior tibio-fibular ligament, which 
connects the back of the head of the fibula with the 
outer tuberosity. 

It is a single broad band and is covered by the tendon 
of the popliteus muscle. A synovial membrane lines this 
joint, which often communicates with the synovial mem- 
brane of the knee-joint of the tibia. 
Middle articulation. 

These bones are joined, in the region of their shafts, 
by an interosseous membrane which connects the con- 
tiguous borders of the tibia and the fibula. 

This membrane is perforated, high up, for the passage 
of the anterior tibial vessels, and, below, for the passage 
of the anterior peroneal vessel. 
Inferior articulation. 

This is a amphi-art hrodial Joint, the two bones being 
flat, smooth, and covered with cartilage, below, to the 
extent of about two lines. 

The ligaments of this articulation are four in number, 
as follows : 

i. The anterior inferior tibio-fibular ligament, which 
connects the front portion of the external malleolus with 
the front portion of the lower end of the tibia. This 
ligament is flat and triangular in form, its broadest part 
being below. It lies in contact with the cartilage cover- 
ing the astragalus. 



THE AHKLE-JOINT. ig* 

2. The posterior inferior tibio-fibular ligament, which 
connects the back part of the external malleolus with the 
back part of the lower end of the tibia, and is similarly- 
arranged to the anterior. 

3. The interosseous ligament, which connects the con- 
tiguous rough surfaces of the tibia and the fibula, and 
which forms the chief bond of union between the bones. 

4. The transverse ligament, which connects the back 
portion of the external malleolus with the back portion 
of the tibia, near to the internal malleolus. 

The synovial membrane of this joint is derived from that of 
the ankle-joint. 

The Ankle- Joint. 

This is a ginglymus articulation between the astragulus and 
the lower extremities of the tibia and the fibula. The two mal- 
leoli of these bones enter prominently into this articulation. 

The ligaments of this joint are four in number as follows : 

1. The anterior ligament, which connects the tibia 
with the astragalus, by the margins of their articular 
surfaces. 

2. The posterior ligament, the fibres of which are 
mainly transverse and which is continuous with the 
inferior posterior tibio-fibular ligament. 

3. The internal lateral ligament, which is also called 
the deltoid ligament. This ligament consists of a 
superficial set of fibres, which connect the internal 
malleolus of the tibia with the inner part of the scaph- 
oid, the lesser process of the os calcis, the back part 
of the inner surface of the astragulus, and the inferior 
calcaneo-scaphoid ligament ; and a deep set of fibres 
which connect the apex of the internal malleolus of 
the tibia with the inner surface of the astragalus. 

4. The external lateral ligament. This ligament 
consists of three separate fasiculi, as follows : 

The anterior fasciculus, which connects the external 
malleolus with the astragalus, in front of its articular 
facet. 

The middle fasciculus, which connects the apex of 
the external malleolus with the outer surface of the 
os calcis. 

The posterior fasciculus, which connects the back 
part of the external malleolus with the astragalus, 
behind its external articular facet. 



196 



ARTHROLOGY OR SYNDESMOLOGY. 



The synovial membrane of the ankle-joint invests the inner 
surfaces of the ligaments and sends a prolongation upwards be- 
tween the tibia and the fibula, for a short distance. 

The vessels of the ankle-joint are derived from the malleolar 
branches of the anterior tibial and from the terminal branches of 
the anterior peroneal arteries. 

The nerves of the ankle-joint are derived from the anterior 
tibial nerve. 

The movements of the ankle-joint consist of flexion and exten- 
sion and a slight amount of lateral motion when the foot is ex- 
tended. 

Articulations of the Tarsus. 

Articulations of the bones of the first row. 

The astragalus and the os calcis, form two arthrodial articu- 
lations and are joined by three ligaments, which are as follows: 

1. The interosseous calcaneo-astragalcid ligament ; , which con- 

nects the two bones directly, and which forms the chief 
bond of union. It is one inch in breadth and is very 
thick and strong. 

2. The external calcaneo-astragaloid ligament, which connects 

the two outer surfaces of the bones with each other. 
It lies in front of the middle fasciculus of the external 
lateral ligament of the ankle-joint. 

3. The posterior calcaneo-astragaloid ligament, which connects 

the back part of the astragalus with the upper portion 
of the os calcis. It is a short, narrow band and is 
directed obliquely backwards and inwards. 
The synovial membranes of this joint are two in number, one 
to each articulation. The anterior synovial membrane is continued 
between the astragalus and the scaphoid. 
Articulation of the bones of the second row. 
The scaphoid, the cuboid and the three cuneiform bones, 
are connected by arthrodial articulations, the ligaments of which 
may be divided into three sets as follows : 

1. The dorsal set, which are numerous small bands somewhat 

irregular in their attachments, which pass from each 
bone to the neighboring bones. 

2. The plantar set, which are less dense than the dorsal, and 

which are also irregularly attached. 

3. An interosseous set, which are four in number and which 

connect the three cuneiform bones with the cuboid 
and with each other, and also the scaphoid and the 
cuboid bones. They are arranged as follows : 



JOINTS OF THE TARSUS. \ gy 

The first connects the sides of the scaphoid and 
cuboid bones. 

The second connects the sides of the internal and 
middle cuneiform bones. 

The third connects the sides of the middle and 
external cuneiform bones. 

The fourth connects the external cuneiform bone 
to the cuboid. 
Articulation of the two rows of tarsal bones. 
Two arthrodial articulations are present between the two rows 
of the tarsus ; the first of which exists between the astragalus 
and the scaphoid bones, and the second between the os calcisand 
the cuboid bone. 

The ligaments of these articulations are seven in number, and 
may be enumerated as follows : 

1. The superior astragalo-scaphoid ligament, which connects 

the upper surfaces of the astragalus and the scap- 
hoid. 

2. The superior calcaneo-cuboid ligament, which also connects 

the os calcis and cuboid bone, on their superior aspect. 

3. The long calcaneo-cuboid ligament, which connects the 

under surface of the os calcis with the bases of the 
2d, 3d, and 4th metatarsal bones. It is the longest 
ligament of the tarsus. It converts the groove, on the 
under surface of the cuboid bone, into a canal for the 
passage of the tendon of the peroneus longus muscle. 

4. The short calcaneo-cuboid ligament, which connects the 

under surfaces of the os calcis and the cuboid bones. 
This ligament is very broad and is lined by the syno- 
vial membrane which exists in the articulation between 
these bones. 

5. The interosseous or internal calcaneo-cuboid ligament, which 

directly connects the os calcis and the cuboid bones. 
It is very broad and strong and is blended, at its 
origin, with the superior calcaneo-scaphoid ligament. 

6. The superior calcaneo-scapJioid ligament, which connects 

the os calcis with the outer side of the scaphoid bone. 
This ligament and the internal calcaneo-cuboid liga- 
ment arise from the same point, and by separating, in 
front, form a resemblance to the letter Y. 

7. The inferior calcaneo-scaphoid ligament, which connects the 

os calcis with the under surface of the scaphoid bone. 
This ligament is lined, upon its upper surface, by a 



198 



ARTHROLOGY OR SYiVDESMOLOGY. 



synovial membrane continued from the anterior cal- 
caneo-astragaioid articulation. 
The articulation between the astragalus and the scaphoid is 
the only enarthrodial joint of the tarsus. In this joint, the round 
head of the astragalus is received into a concavity formed by the 
following structures : 

1. The posterior surface of the scaphoid. 

2. The anterior articulating surface of the os calcis. 

3. The upper surface of the calcaneo-scaphoid ligament. 

It possesses only one ligament, the superior astragalo-scaphoid, 
which is a broad band connecting the neck of the astragalus with 
the upper surface of the scaphoid. The inferior calcano-scaphoid 
ligament supplies the place of an inferior ligament to this joint. 

The synovial membranes of the tarsus are four in number, and 
are situated as follows : 



r One for the posterior calcaneo-astragaioid articulation. 
One for the two fol- j Anterior calcaneo-astragaioid articulation. 

lowing points :. . . { Astragalo-scaphoid articulation. 
One for the calcaneo-cuboid articulation. 

'Articulation of the scaphoid and the three cuneiform 
bones. 
The articulations of the three cuneiform bones. 
The articulation of the external cuneiform bone and 

the cuboid. 
The articulations of the middle and external cunei- 
form bones and the bases of the second and third 
metatarsal bones. 



Synovial mem- 
branes of the 
tarsus 



One for the fol- 
lowing points : 



Tarso-Metatarsal Articulations. 

* This set of articulations comprises a number of arthrodial 
joints, which are formed as follows : 

1st metatarsal bone and internal cuneiform. 
2d metatarsal bone and all three cuneiform bones. 
3d metatarsal and external cuneiform. 
4th metatarsal and external cuneiform and cuboid. 
5th metatarsal bone and cuboid. 
As is perceived in the second of these articulations, the three 
cuneiform bones form a deep recess into which the second meta- 
tarsal bone is received. This fact renders disarticulation of the 
tarsal bones from the metatarsus extremely difficult. 

The ligaments, which enter into the formation of these above 
named joints, may be divided into three sets as follows : 

I. A dorsal set, which connect each metatarsal bone with the 
corresponding tarsal bone. The second metatarsal 
bone has three dorsal ligaments, one for each of the 
cuneiform bones. 



METATARSAL ARTICULATION'S. 



I99 



2. A plantar set, which serve the same purpose, on the plan- 

tar aspect of the foot, but which are thinner and less 
regular in their situation. 

3. An interosseous set, which comprises three strong ligaments, 

one of which is situated between the second metatar- 
sal bone and the internal cuneiform bone, and the 
other two between the external cuneiform bone and 
the second and third bones of the metatarsus. 

Metatarso-Metatarsal Articulations. 

The metatarsal bones, like the metacarpal, are connected with 
each other both at their tarsal and at their digital extremities. 
Tarsal extremities. 

The 1st and 2d metatarsal bones do not come into 
contact at their tarsal extremities, but between the other 
metatarsal bones arthrodial articulations exist. 

The ligaments of these articulations comprise three 
sets namely, a dorsal, a plantar and an interosseous set. 
Digital extremities. 

These extremities of the metatarsal bones are all 
joined together by a transverse band, which crosses the 
whole width of the metatarsus, and which is called the 
transverse metatarsal ligament. 

Metatarsophalangeal Articulations. 

These articulations differ, in no way, from those of the meta- 
carpophalangeal articulations which are described in previous 
pages of this volume. 

The ligaments of the joints are also similar, and are two in 
number, viz. 

1. The anterior or glenoid ligments. 

2. The lateral ligaments (two for each joint). 

Phalangeal Articulations. 

These ginglymoid joints are similar to those of the fingers and 
the ligaments of each of them correspond to those of the meta- 
carpophalangeal articulations. 

Points of Surgical Interest in the Region of the Foot. 

The level of the ankle joint lies one half inch above the tip of 
the inner malleolus. 

The two malleoli are the surgical guides to the ankle joint, and 
present points of difference which are deserving of special notice. 



200 ARTHROLOGY OR SYNDESM0L0GY. 

The outer malleolus descends lower than the inner, and thus 
locks the joint upon its outer side. The inner malleolus advances 
more to the front, but, being broader than the outer malleolus, 
its posterior border corresponds with that of the outer. 

In Syme's amputation, the incision should therefore run from 
the apex of the outer malleolus to the middle point of the inner. 

A valuable guide in adjustiitg a fracture of the lower extremity 
below the knee joint, may be afforded, by remembering that the 
inner edge of the patella, the inner malleolus, and the inner border 
of the large toe should be in the same vertical plane, provided 
that the leg be well formed. 

The tubercle of the scaphoid bone is the surgical guide to the 
astragalo-scaphoid articulation, and is, therefore, on the line of 
the amputation of Chopart. 

The point of articulation between the internal cuneiform bone 
and the metatarsal bone of the great toe lies about one and a half 
inches in front of the tubercle of the scaphoid bone. 

The calcaneo-scaphoid ligament forms a portion of the recepta- 
cle or socket into which the scaphoid bone is placed. 

The articulation between the os calcis and the cuboid bone 
lies midway between the tip of the external malleolus and the 
tarsal extremity of the $th metatarsal bone. 

The projection of the fifth metatarsal bone is the guide to 
the articulation of that bone with the cuboid. 

In amputating the toes from the metatarsal bones, it should 
be remembered that the folds of skin, between the toes, lie one 
inch in front of the articulation. 

The power of producing adductio7i of the foot, which is pos- 
sessed by the tendo Achillis, depends upon the peculiar confor- 
mation of the articulating surfaces between the os calcis and the 
astragalus. 



MYOLOGY. 



MUSCLES IN GENERAL. 



203 



MYOLOGY. 

The muscles are the active organs of motion, constituting the 
source of power that is applied to the various levers represented 
by the component parts of the skeleton. The movements pro- 
duced are the result of that peculiar property, possessed by mus- 
cles, of shortening themselves, which is called muscular con- 
tractility. 

Muscles are of two great classes. 

A. Muscles of Animal Life or Voluntary Muscles. 

B. Muscles of Organic Life or Involuntary Muscles. 
The first class are under the control of the will, and comprise 

the muscles of locomotion, respiration, expression and some others. 
The second class are entirely withdrawn from the control of the 
will, such as those of the heart, of the arteries, of the intestinal 
canal, and of the various organs. When we employ the term 
" muscular system " we refer to the first class or voluntary muscles. 

The muscles of the body may be connected either with the 
bony skeleton, the ligaments of joints, the cartilaginous structures 
or the integument. When attached to ligaments only, do muscles 
come in direct contact, however, with the part on which they are 
destined to act, since, when attached to bone and cartilage, the 
fibres are connected with the periosteum and perichondrium, and, 
when the action of the muscle is directed upon the integument, 
the fibres are usually connected with the subcutaneous areolar 
tissue. 

Muscles vary greatly, (1) in their general form, (2) in their 
method of arrangement as regards their tendon, and (3) in their 
size. 

The various forms of muscles are influenced by their situation 
and the function which they are destined to perform. In the 
limbs, they are usually of an elongated form, when superficially 
situated, and broad, when deeply placed. In the trunk, they are, 
as a rule, broad, flattened or expanded, since they form either the 
parietes of cavities or are spread out upon the bony wall of the 
chest or pelvis. We therefore employ such terms as long, short, 
broad, expanded, etc., as indicating peculiar conformations or types 
of muscles. 

As regards the arrangement of the muscular fibres to the ten- 
dons to which they are attached, an equal diversity is perceived. 
The long muscles usually present a tendon at either one or both 
extremities, towards which longitudinal fibres converge. When 
shorter fibres converge to the side of a tendon, which runs for the 



204 



MYOLOGY. 



whole length of a muscle, like the plumes of a pen, the name 
penniform is applied. Examples of this type are present in the 
peronei muscles. 

If short fibres converge to both sides of a tendon, which 
extends for its whole length, the muscle is called bipenniform, as 
in the rectus femoris, while a muscle is said to be radiated, when 
its fibres converge from a broad, flat surface to a narrow tendinous 
insertion, as in the temporal muscle. 

The nomenclature of muscles is defective and often confusing. 
Muscles may be named (i) from their situation ; as the peroneus, 
tibialis, etc. (2) From their form, as the trapezius, triangularis, del- 
toid, etc. (3) From their function, as flexors, extensors, pronators, 
abductors, levators, tensors, etc. (4) From their attachments, as 
the sterno-mastoid, sterno-hyoid, sterno-thyroid, etc. (5) From 
their divisions, as the biceps, triceps, digastric, complexus, etc. 

In all voluntary muscles and also in the muscular fibres of the 
heart, the primitive fasiculi present fine dark lines or strice run- 
ning transversely across the fibre in curved or parallel lines. 
Longitudinal striae are also detected, but these mark only the 
direction and number of the ultimate fibres or fibrillae. 

The striated variety of muscular fibre is present in all the vol- 
untary muscles, and also in those of the pharynx, the larynx, 
the upper half of the oesophagus, the heart, the walls of the venae 
cavae and the muscles of the ear. 

The unstriped or involuntary muscular fibres are found in the 
lower half of the oesophagus, and the whole of the remaining 
gastro-intestinal tract ; in the trachea and the bronchi ; in the 
gall bladder and the ductus communis choledochus ; in the pelvis 
and the calices of the kidney, the ureters, the bladder and the 
urethra ; in the female sexual organs, viz., the vagina, the clitoris, 
the uterus, the Fallopian tubes and the broad ligaments ; in the 
male sexual organs, viz., the penis, the urethra, the prostate gland, 
Cowper's ducts, the vesiculae seminales, the vas deferens, the 
epididymis and the dartos ; in the skin and mucous membranes ; 
in the ducts of certain glands, as in Wharton's and Cowper's 
ducts ; and finally in the walls of the arteries, veins and lym- 
phatics. 

The muscles may be divided for the sake of convenience of 
description, into the four following classes, as follows : 

A. Muscles of the Head and Neck. 

B. " " TRUNK. 

C. " " UPPER extremity. 

D. " " LOWER extremity. 



MUSCLES OF THE HEAD. 



205 



In the following pages will be found enumerated and classi- 
fied the various muscles comprised under each of these heads* 
and a statement of those anatomical facts pertaining to the indi- 
vidual muscles which are of practical importance and value. 

DIVISION I. 

MUSCLES OF THE HEAD AND NECK. 



(A.) 
MUSCLES OF THE HEAD. 

The muscles of the head may be arranged under seven distinct 
groups. They comprise 31 pairs and one single muscle. 
The seven groups above mentioned are as follows : 



I pair. \ Occipito-frontalis. 

{Attollens aurem. 
Attrahens aurem. 
Retrahens aurem. 
( Corrugator supercilii. 
.3 pairs. -< Orbicularis palpebrarum. 
( Tensor tarsi. 
Pyramidalis nasi. 
Levator labii superioris et nasi. 
Compressor naiis. 
[ Depressor labii superioris et nasi. 
' Levator palpehrse superioris. 
Rectus superior. 
Rectus inferior, 

V. Orbital group .....7 pair. \ Rectus interims. 

I Rectus externus. 
I Obliquus superior. 
[Obliquus inferior. 



I. Epicranial group 
II. Auricular " 

III. Palpebral 

IV. Nasal 



,4 pairs. 



VI. Labial group. 



.9 pair, 
I single. 



f Levator labii su 



CD 

t^d.) pnus. 



penons pro- 



Levator anguli oris. 
I Zygomaticus major. 
*> ( Zygomaticus minor. 
■< Buccinator. 
Risorius Santorini. 
£ . I Levator menti. 
IjjM Depressor labii inferioris. 
>_) "" ( Depressor anguli oris. 



VII. Maxillary group... .* 



,4 pair. 



Orbicularis oris (single.) 
["Temporal. 
J Masse ter. 
J External pterygoid. 
(^ Internal pterygoid. 



206 MYOLOGY. 

ORIGIN AND INSERTION. 

I. 

EPICRANIAL REGION, 
(i muscle). 
Occipito Frontalis. 

Is a flat, thin muscle, consisting of two fleshy bellies, connected 
by an intermediate tendon or aponeurosis sometimes called the 
" galea capitis." 
Origin. 

From the external two-thirds of the superior curved 
line of the occipital bone and the mastoid process of 
the temporal bone. 
Insertion. 

The inner fibres are blended with those of the 
pyramidalis nasi muscle, the rest of its fibres anasto- 
mosing with the corrugator supercilii, the orbicularis 
palpebrarum and the pyramidalis nasi muscles. 
Nervous supply. 

Facial nerve and sometimes the occipitalis minor. 

II. 
AURICULAR GROUP. 
(3 muscles). 
Attollens Aurem. 
Origin. 

From the aponeurosis of the occipito -frontalis mus- 
cle on the side of the cranium. 
Insertion, 

Into the upper part of the cranial surface of the 
pinna. 
Nervous supply. 

Small occipital branch of the cervical plexus. 

Attrahens Aurem. 
Origin. 

From the lateral aponeurosis of the cranium. 
Insertion. 

Into the front part of the helix. 
Nervous supply. 

Branch of the facial or 7th cranial nerve. 

Retrahens Aurem. 
Origin. 

From the mastoid process of the temporal bon*.. 



MUSCLES OF THE HEAD. 207 

Insertion. 

Into the posterior portion of the cranial surface of 
the concha. 
Nervous supply. 

Branches of the facial or 7th cranial nerve. 

III. 

PALPEBRAL GROUP. 

(3 muscles). 

Orbicularis Palpebrarum. 
Origin. 

1. From the internal angular process of the frontal 
bone and the nasal process of the superior maxillary- 
bone. 

2. From the anterior surface and the borders of 
the tendo oculi. 

Insertion. 

1. Into the skin covering the eyelids, spreading into 
the forehead, temple and cheek. 

2. Into the inner third of the lower edge of the 
orbit. 

3. Into the lower edge of the tendo oculi. 
Action. 

To close the eyelids, to compress the lachrymal sac, 
and to force the tears into the nasal duct. 
Nervous supply. 

Temporal and malar branches of the facial or 7th 
cranial nerve. 

CORRUGATOR SUPERCILII. 
Origin. 

From the inner extremity of the superciliary ridge 
of the frontal bone. 
Insertion. 

Into the deep surface of the orbicularis palpebrarum 
muscle, near the middle of the arch of the orbit. 
Nervous supply. 

Branch of the facial or 7th cranial nerve. 

Tensor Tarsi. 
Origin. 

From the crest and orbital surface of the lachrymal 
bone. 



2oS MYOLOGY. 

Insertion. 

By two slips, into the tarsal cartilage near to the 
puncta lachrymalis. 
Nervous supply. 

Malar branch of the facial or 7th cranial nerve. 

IV. 

NASAL GROUP. 
(5 muscles). 
Pyramidalis. Nasi. 



This muscle is a continuation of the fibres of the 
frontalis muscle. 
Insertion. 

It becomes blended with the compressor naris 
muscle. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 

Levator Labii Superioris Alaeque Nasi. 
Origin. 

From the upper part of the nasal process of the 
superior maxillary bone beneath the tendo-palpebrae. 
Insertion. 

By one slip, into the cartilage of the ala of the 
nose ; by the other slip, it becomes blended, in the 
upper lip, with the orbicularis oris. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 

Compressor Naris. 
Origin. 

From the canine fossa in the surface of the superior 
maxillary bone. 
Insertion. 

It joins its fellow of the opposite side and with the 
pyramidalis nasi. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 

Depressor Alae Nasi. 
Origin. 

From the incisor fossa of the superior maxillary 
bone. 



MUSCLES OF THE HEAD. 200 

Insertion, 

Into the septum and the back part of the ala of the 
nose. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 

Depressor Labii Superioris Alaeque Nasi. 
Origin. 

From the incisor fossa of superior maxillary bone. 
Insertion. 

Into the integument of the »upper lip, and the car- 
tilage of the septum and also of the nose. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 

V. 

ORBITAL GROUP. 

(7 muscles). 

Levator Palpebrae Superioris. 
Origin. 

From the sphenoid bone, in front of the optic 
foramen. 
Insertion. 

Into the upper border of the upper tarsal cartilage. 
Nervous supply. 

Motor oculi or 3d cranial nerve. 

Rectus Superior. 
Origin. 

From the upper margin of the optic foramen, and 
from the sheath of the optic nerve. 
Insertion. 

Into the sclerotic coat of the eyeball. 
Nervous supply. 

Motor oculi or 3d cranial nerve. 

Rectus Externus. 
Origin. 

By two heads. I. From the outer margin of the 
optic foramen. 2. From the ligament of Zinn and the 
lower margin of the sphenoidal fissure. 
Insertion. 

Into the sclerotic coat of eyeball. Between the two 
heads of the muscle pass the following structures. 



2io MYOLOGY. 

1. The 3d cranial nerve. 

2. Nasal branch of the 5th cranial nerve. 

3. The 6th cranial nerve. 

4. Ophthalmic vein. 
Nervous supply. 

The abducens or 6th cranial nerve. 

Rectus Internus. 
Origin. 

From the ligament of Zinn. 

Insertion. 

Into the sclerotic coat of the eyeball. 
Nervous supply. 

Lower division of the motor oculi or 3d cranial nerve. 

Obltquus Superior. 
Origin. 

About a line above the inner margin of the optic 
foramen. 
Insertion. 

Into the sclerotic coat at the outer part of the 
globe of the eye, the tendon first passing through a 
pulley, near the internal angular process of the frontal 
bone. 
Nervous supply. 

The patheticus or 4th cranial nerve. 

Obliquus Inferior. 
Origin. 

From a depression in the orbital plate of the supe- 
rior maxillary bone, external to the lachrymal groove. 
Insertion. 

Into the outer part of the sclerotic coat of the 
eyeball. 
Nervous supply. 

The lower division of the 3d cranial nerve. 

VI. 

LABIAL GROUP. 
(9 pairs and one single muscle.) 

Levator Labii Superioris Proprius. 
Origin. 

From the lower margin of the orbit, immediately 
above the infra-orbital foramen ; and from the adjoin- 
ing surface of the malar bone. 



MUSCLES OF THE HEAD. 211 

Insertion. 

Into the skin and the muscular substance of the 
upper lip. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 
Action. 

This muscle is supposed to render the hair erect, 
as in the feline tribes, 

Levator Anguli Oris. 
Origin. 

From the canine fossa of the superior maxillary- 
bone, immediately below the infra-orbital foramen. 
Insertion. 

In common with the zygomaticus major, the orbi- 
cularis oris, and the depressor anguli oris, into the 
angle of the mouth. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 

Zygomaticus Major. 
Origin. 

From the malar bone, in front of the zygomatic 
suture. 
Insertion. 

Into the angle of the mouth. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 

Zygomaticus Minor. 



From the anterior part of the malar bone immed- 
iately behind the maxillary suture. 
Insertion. 

In common with that of the levator labii superioris. 
Nervous supply. 

Infra-orbital branch of the facial or 7th cranial nerve. 

Buccinator. 
Origin. 

1. From the outer surface and border of the alveo- 
olar process of the superior maxillary bone. 

2. From the inferior maxillary bone, from the first 
molar tooth to the last. 

3. From the pterygo-maxillary ligament. 



212 MYOLOGY. 

Insertion. 

Into the angle of the mouth, its fibres blending with 
those of the orbicularis oris, the zygomatic and the 
depressor anguli oris. 
Action. 

By pressing the cheeks inward, to assist in articula- 
tion, mastication, blowing or sucking. 
Nervous supply. 

The facial or 7th cranial nerve and the buccal branch 
of the inferior maxillary nerve. 

Levator Labii Inferioris. (Levator Menti.) 
Origin. 

From the incisor fossa of the inferior maxillary 
bone, external to the symphysis of the lower jaw. 
Insertion. 

Into the integument of the lower lip. 
Nervous supply. 

The facial or 7th cranial nerve. 

Depressor Labii Inferioris. (Quadratus Menti.) 
Origin. 

From the external oblique line of inferior maxillary 
bone. 
Insertion. 

Into the integument of the lower lip. 
Nervous supply. 

The facial or 7th cranial nerve. 

Depressor Anguli Oris. (Triangularis Menti.) 
Origin. 

From the external oblique line of inferior maxillary 
bone. 
Insertion. 

Into the angle of the. mouth. 
Nervous supply. 

The facial or 7th cranial nerve. 
Orbicularis Oris. 

Is the sphincter muscle of the mouth and consists of two 
portions, an upper and lower portion, one for each lip, which 
have attachments to the superior and inferior maxillary bones. 
The fibres of each of the semicircular planes situated in the lips, 
decussate at the angle of the mouth and unite with the decus- 
sating fibres of the buccinator. The fibres at the free margin of 
the lips are continued uninterruptedly from one lip to the other. 



MUSCLES OF THE HEAD. 



213 



RlSORIUS. 
Origin. 

From the fascia upon the masseter muscle or upon 
the parotid gland. 
Insertion. 

Into the orbicularis oris and the depressor anguli 
oris muscles. 
Nervous supply. 

Supra-maxillary branch of the facial or 7th cranial 
nerve. 
This muscle is regarded, by some anatomists, as a portion of 
the platysma myoides muscle. 

VII. 

MAXILLARY GROUP. 

(4 muscles). 
Temporal. 
Origin, 

From the temporal fossa and the temporal aponeu- 
rosis. 
Insertion. 

Into the coronoid process of the inferior maxillary 
bone and sometimes into the inner portion of the 
ramus of the jaw. 
Nervous supply. 

The inferior maxillary division of the 5th cranial 
nerve. 

Masseter. 
Origin. 

1. From the anterior two-thirds of the zygoma, and 
from the malar process of the superior maxillary bone. 

2. From the inner surface of the zygoma. 
Insertion. 

Into the angle of the jaw, the external surface of the 
ramus, and the external surface of the coro/ioid process 
of the jaw. 
Nervous supply. 

The inferior maxillary division of the 5th cranial 
nerve. 

External Pterygoid. 

This muscle consists of two distinct portions, each of which 
has a different point of origin. 



214 MYOLOGY. 

Origin. 

1. From the outer surface of the external ptery- 
goid plate and greater wing of the sphenoid. 

2. From the tuberosities of the palate bone and the 
superior maxillary bone. 

Insertion. 

Into a fossa on the anterior surface of the neck of 
the condyle, and into the edge of the interarticular 
fibro-cartilage of the temporo-maxillary articulation. 
Nervous supply. 

The inferior maxillary division of the 5th cranial 
nerve. 
The internal maxillary artery passes between its two heads. 
Internal Pterygoid. 
Origin. 

1. From a fossa between the two pterygoid plates of 
the sphenoid bone. 

2. From the hamular process of the sphenoid bone. 

3. From the tuberosity of the palate bone. 
Insertion. 

Into the angle and inner surface of the lower jaw, as 
high as the dental foramen. 
Nervous supply. 

A branch from the anterior division of the inferior 

maxillary nerve. 

The first two muscles of this group tend to shut the lower 

jaw tightly upon the upper jaw. The last two muscles of this 

group tend to create a horizontal motion of the lower jaw, when 

acting alternately upon either side and not conjointly. 

The gustatory, dental and chorda tympani nerves lie in close 
relation to the internal pterygoid muscle, as do also the internal 
maxillary artery and vein. 

ACTION OF THE MUSCLES OF THE HEAD, 

The muscles of the head may be classified secondly, on a basis 
of the function chiefly performed by them as follows : 

I. Muscles of expression, 20 pairs and 1 single muscle, under 

which may be enumerated : 



The epicranial 


group 




I pair. 


" auricular 


<< 




3 pairs. 


" palpebral 


<« 




3 " 


" nasal 


n 




4 " • 


" labial 


11 




J. " 






Total, 


20 " of muscles. 



MUSCLES OF THE- NECK. 



215 



The " obicularis oris " muscle, (single.) 

II. Muscles of vision. 

The orbital group. 7 pairs. 

III. Muscles of mastication. 

The maxillary group. 4 pairs. 

The labial group of muscles, which have been classed as mus- 
cles of expression, assists also in mastication and in the acts of 
talking and singing, but they have been classified as muscles of 
expression, since, as a group, this seems a most important 
function. 
NERVOUS SUPPLY OF THE MUSCLES OF THE HEAD. 

Of these several groups of muscles, the motor nerves of the 
epicranial, the auricular, the palpebral, the nasal, and the labial 
groups (in all twenty pairs and one single muscle) are derived 
from one nerve, viz., the facial or 7th cranial nerve. 

The maxillary group also derives its motor power from one 
nerve, viz., the anterior or smaller branch of the inferior max- 
illary division of the $th cranial nerve, while all the muscles of the 
orbit are supplied by the motor oculi or ^rd cranial nerve, except 
the superior oblique and the external rectus muscles, the former 
of which is supplied by the 4th cranial nerve and the latter by the 
6th cranial nerve, 

B. 
MUSCLES OF THE NECK. 

The muscles of the neck consist of 45 pairs and one single 
muscle. They may be arranged in 9 classes or groups. 

I. Superficial lateral group : 2 pairs, j gj jS^ekkSStoid. 

f Sternohyoid. 

n T r , , . , . I Sterno-thvroid. 

. Infra or sterno-hyoid group : 4 pairs. -< ~ , r .- , 

[Thyro-hyoid. 

'Anterior belly of digastric. 

Mylo-hyoid. 

Geniohyoid. 

Genio-hyo-glossus. 

Hyo-glossus. 

Lingualis. 
("(Posterior belly of digastric) 
IV. Submaxillary ox stylo-hyoid gxonp : 3 pairs. •< « t 1 1 

[ Stylo- pharyngeus. 
fLongus colli. 

Rectus capitis amicus major. 
j Rectus capitis amicus minor. 

V. Prevertebral group : 7 pairs. -J Rectus capitis lateralis. 

I Scalenus amicus. 
I Scalenus niedius. 

(^ Scalenus posticus. 



III. Su/>ra or genio-hyoid group : 6 pairs. 



2i6 MYOLOGY. 



VI. Posterior cervical group : 8 pairs. ■< 



'"Splenius capitis. 

Trachelo-mastoid, 

Complexus. 

Biventer cervicis. 

Obliquus capitis superior. 

Obliquus capitis inferior. 

Rectus capitis posticus major. 

Rectus capitis posticus minor, 
f Tensor palati. 
J Levator palati. 
VII. 'Muscles of palate : 5 pairs. \ Palato-glossus. 

Palato-pharyngeus. 
I^Azygos uvulae. 

{Superior constrictor. 
Middle constrictor. 
Inferior constrictor, 
f Crico- thyroid, 
f Acting on vocal \ Crico- arytenoid posticus. 
I cords : 4 pairs and-( Crico-arytenoid lateralis. 
IX. Muscles of the la- \ 1 single muscle. | Thyro-arytenoid. 

rynx: 7 pairs and I \ [_ Arytenoideus, (single), 

single. Acting upon epi- i Aryteno epiglottideus superior. 

I glottis : 3 pairs of ■] Aryteno-epiglottideus inferior. 
I muscles. ( Thyro-epigiottideus. 

ORIGIN AND INSERTION. 

SUPERFICIAL LATERAL GROUP. 
(2 muscles). 
Platysma Myoides. 
Origin. 

From the clavicle, the acromion process of the 
scapula, and the subcutaneous fascia over the pector- 
alis major and deltoid muscles. 
Insertion. 

Into the chin, the lower jaw, and the fascia covering 
the parotid gland. 
Nervous supply. 

Superficial branches of the cervical plexus and 
branches of the infra-maxillary division of the facial 
or 7th cranial nerve. 

Sterno-Cleido-Mastoid. 
Origin. 

From the inner third of the clavicle and, by a ten- 
don, from the first bone of the sternum. 
Insertion. 

Into the mastoid process of temporal bone and the 
superior transverse ridge of the occipital bone. 
Nervous supply. 

The deep external branches of the cervical plexus and 
branches of the spinal accessory or nth cranial nerve. 



MUSCLES OF THE NECK. 2 \J 

The ster no-mast oid muscle is an important guide to the carotid 
arteries, since its internal border is nearly parallel with the com- 
mon carotid artery and since the muscle can be rendered very 
prominent, by the head being turned towards the opposite 
shoulder. Between the sternal and clavicular points of origin of 
this muscle, may be perceived, in all necks that are not particu- 
larly fleshy, a fossa called the fonticulus gutturis, since it rises and 
falls during respiration, especially if labored breathing exists. 

INFRA OR STERNO-HYOID GROUP. 

(4 muscles). 
Sterno-Hyoid. 
Origin. 

From the inner extremity of the clavicle, the pos- 
terior surface of the first bone of the sternum, the car- 
tilage of the 1st rib and the sternal end of the clavicle. 
Insertion. 

Into the lower border of the body of the hyoid bone 
Nervous supply. 

A branch from the loop between the descendens 
noni nerve and the communicans noni nerve. 

Sterno-Thyroid. 
Origin. 

From the posterior surface of the sternum and the 
cartilage of the 1st rib. 
Insertion. 

Into the oblique line on the ala of the thyroid car- 
tilage. 
Nervous supply. 

A branch from the loop between the descendens 
noni nerve and the communicans noni nerve. 

Thyro-Hyoid. 
Origin. 

From the oblique line on the ala of the thryoid car- 
tilage. 
Insertion. 

Into the lower border of the body of the hyoid 
bone and its greater cornu. 
Nervous supply. 

A branch of the hypoglossal or 12th cranial nerve. 
OMO-HYOID. 
Origin. 

From the upper border of the scapula, near the supra 



218 MYOLOGY. 

scapular notch, and, occasionally, from the ligament 
which crosses the notch. 
Insertion. 

Into the lower border of the body of the hyoid bone. 
Nervous supply. 

From three sources, viz., the hypoglossal or 12th 
cranial nerve, a filament of the pneumogastric or ioth 
cranial nerve, and a filament from the cervical plexus 
of nerves. It is thus associated (i) with the move- 
ments of the tongue, (2) with the function of respira- 
tion, and (3) with the movements of the muscles of 
the neck. 
The central tendon of this muscle is attached to the clavicle 
by the deep cervical fascia, which forms a loop about it. 

The omo-hyoid muscle, in long and thin necks, may be dis- 
cerned through the skin as a cord running parallel with and above 
the line of the clavicle, and rising and falling with the acts of in- 
spiration and of expiration. It renders tense that portion of the 
cervical fascia, which lies over the apex of the lung, and its pos- 
terior belly is, by some anatomists, considered as analogous to a 
serration of the serratus magnus ; its central tendo?i to a rudi- 
mentary cervical rib ; and its anterior belly, to a sterno-hyoid 
muscle. It is a guide to the seat of election in the operation for 
ligation of the common carotid artery. 

SUPRA OR GENIOHYOID GROUP. 

(6 muscles). 

Digastric. 

This muscle consists of two elongated muscular bellies, united 
by an intervening rounded tendon. It extends from the mastoid 
process of the temporal bone to the symphysis of the lower jaw. 
Origin. 

The posterior belly arises from the digastric groove, 
on the inner side of mastoid process of the temporal 
bone, and the anterior belly from a fossa on the inner 
side of the symphysis of the chin. 
Insertion. 

The central tendon is attached to the body and 
greater cornu of the hyoid bone, by a broad band of 
aponeurotic fibres, in the form of a loop, lined by a syn- 
ovial membrane. The posterior belly passes through 
the stylo-hyoid muscle. 



MUSCLES OF THE NECK. 



219 



Nervous supply. 

The posterior belly is supplied by the facial or 7th 
cranial nerve, and the anterior belly by the mylo-hyoid 
branch of the inferior dental nerve. 
Mylo-Hyoid. 

Origin. 

From the whole length of the mylo-hyoid ridge of 

the lower jaw, from the symphysis, in front, to the last 
molar tooth, behind. 
Insertion. 

Into the whole length of the body of hyoid bone 
and into a tendinous line from that bone to the chin. 
Nervous supply. 

The mylo-hyoid branch of the inferior dental nerve. 
This muscle, with its fellow of the opposite side, forms th.^ floor 
of the mouth. 
Genio-Hyoid. 
Origin. 

From the inferior genial tubercle, on the inside of 
the symphysis of the lower jaw. 
Insertion. 

Into the anterior surface of the body of the hyoid 
bone. 
Nervous supply. 

The hypoglossal or 12th cranial nerve. 

Genio-Hyo-Glossus. 
Origin. 

From the superior genial tubercle, on the inner side 
of the symphysis of the chin. 
Insertion, 

1. Into the body of the os-hyoides. 

2. Into the pharynx, between the hyoid bone and 
• styloglossus muscle. 

3. Into the under surface of the tongue. 
Nervous supply. 

The hypoglossal or 1 2th cranial nerve. 
Actio' 1. 

To depress the middle of the tongue. 
This muscle has been divided to relieve stammering. 
Hyo-Glossus. 
Origin. 

From the body and the greater and the lesser cor- 
nua of the hyoid bone. 



220 MYOLOGY. 

Insertion .- 

Into the side of the tongue, between the lingualis 
and stylo-glossus muscles. 
Nervous supply. 

The hypoglossal or 12th cranial nerve. 

Action. 

To depress the sides of the tongue and render the 
dorsum of the tongue convex. 

LINGUALIS. (Superior set of fibres.) 

This muscle consists of a longitudinal set of fibres 
running from the base to the apex of the tongue, be- 
tween the genio-hyo-glossus and the stylo-glossus and 
hyo-glossus muscles. Some of its fibres are lost on the 
base of the tongue and others are attached occasionally 
to the hyoid bone. 
Nervous supply. 

Chorda tympani branch of the facial or 7th cranial 
nerve. 
Action. 

To render the dorsum of the tongue convex by 
drawing its extremities together. 

SUB-MAXILLARY OR STYLO-HYOID GROUP. 
(3 muscles). 
Stylo-Hyoid. 
Origin, 

From the posterior part of the styloid process of the 
temporal bone, near to its base. 
Insertion. 

Into the body of the hyoid bone, at its junction with 
the great cornu. 
Nervous supply. 

A branch of the facial or 7th cranial nerve. 
Action. 

To raise and draw backwards the hyoid bone and 
the tongue. 

Stylo-Glossus. 
Origin. 

From the styloid process and the stylo-maxillary 
ligament. 
Insertion. 

1. Into the side of the tongue, from the palatoglos- 
sus muscle to the tip. 



MUSCLES OF THE NECK. 221 

2. Into the transverse fibres of the tongue, by sepa- 
rating the fibres of the hyo-glossus muscles. 
Nervous supply. 

The hypoglossal or 1 2th cranial nerve. 

Stylo-Pharyngeus. 
Origin. 

From the base of the styloid process of the tempo- 
ral bone. 
Insertion. 

i. Into the posterior border of the thyroid car- 
tilage. 

2. Into the sides of the pharynx. 
Nervous supply. 

Glosso-pharyngeal or 9th cranial nerve and also 
branches of the pharyngeal plexus. 
Action. 

To elevate and widen the pharynx. 

PREVERTEBRAL GROUP. 
(7 muscles). 

Longus Colli. 

1. Vertical portion. 

Origin. From the bodies of the three upper dorsal 
and the lower cervical vertebrae, and the inter-verte- 
bral cartilages. 

Insertion. Into the bodies of 2nd, 3rd and 4th cer- 
vical vertebrae. 

2. Superior oblique portion. 

Origin. From the anterior tubercles of the trans- 
verse processes of the 3rd, 4th, and 5th cervical ver- 
tebrae. 

Insertion. Into the tubercle on the anterior arch 
of the atlas. 

3. Inferior oblique portion. 

Origin. From the bodies of the two upper dorsal 
vertebrae. 

Insertion. Into the transverse processes of the 5th 
and 6th cervical vertebrae. 
Nervous supply. 

One of the branches of the brachial plexus, given 
off above the clavicle. 



222 MYOLOGY. 

Rectus Capitis Anticus Major. 

Origin. 

From the anterior tubercles of the transverse pro- 
cesses of the 3rd, 4th, 5th, and 6th cervical vertebrae. 
Insertion. 

Into the basilar process of the occipital bone. 
Nervous supply. 

The sub-occipital nerve and the deep branches of 
the cervical plexus. 

Rectus Capitis Anticus Minor. 
Origin. 

From the anterior surface, the lateral mass, and the 
transverse process of the atlas. 
Insertion. 

Into the basilar process of the occipital bone. 
Nervous supply 

The sub-occipital nerve and the deep branches of 
the cervical plexus. 

Rectus Capitis Lateralis. 
Origin. 

From the upper surface of the transverse process of 
the atlas. 
Insertion. 

Into the jugular process of the occipital bone. 
Nervous supply. 

The sub-occipital nerve. 
Scalenus Anticus. 
Origin. 

From the tubercle on the inner border and upper 
surface of the 1st rib. 
Insertion. 

Into the anterior tubercles of the transverse processes 
the of 3rd, 4th, 5th and 6th cervical vertebrae. 
Nervous supply. 

A supra-clavicular branch of the brachial plexus. 

Scalenus Medius. 
Origin. 

From the 1st rib, behind the groove for the subcla- 
vian artery. 
Insertion. 

Into the posterior tubercles of the transverse pro- 
cesses of the six lower cervical vertebrae. 



MUSCLES OF THE NECK. 223 

Nervous supply. 

A supra-clavicular branch of the brachial plexus. 

Scalenus Posticus. 
Origin. 

From the outer surface of the 2nd rib, behind the 
origin of the serratus magnus muscle. 
Insertion. 

Into the posterior tubercles of the transverse pro- 
cesses of the two or three lower cervical vertebrae. 
Nervous supply. 

A supra-clavicular branch of the brachial plexus. 

POSTERIOR CERVICAL GROUP. 

(8 muscles). 

Splenius Capitis et Colli. 
Origin* 

From the ligamentum nuchae, the 7th cervical ver- 
tebra, and the spinous processes of the 1st, 2nd, 3rd, 
4th and 5 th dorsal vertebrae, 
Insertion. 

Into the posterior tubercles of the transverse pro- 
cesses of the three upper cervical vertebrae ; also into 
the mastoid process of the temporal bone, the superior 
curved ridge of the occipital bone and a rough space 
below it. 
Nervous supply. 

Posterior branches of the cervical nerves. 

Trachelo-Mastoid. 
Origin. 

From the articular processes of the last four cervical, 
and the transverse processes of the first four dorsal 
vertebrae. 
Insertion. 

Into the posterior margin of the mastoid process of 
the temporal bone. 
Nervous supply. 

Posterior divisions of the spinal nerves. 
COMPLEXUS. 
Origin. 

From the transverse processes of the last cervical 
and the four or five upper dorsal vertebrae. 



224 MYOLOGY. 

From the articular processes of the 4th, 5th, 6th, 
and 7th cervical vertebrae. 
Insertion. 

Into the occipital bone, between the two curved 
lines on its inferior surface. 
Nervous supply. 

From three sources, viz., the great occipital nerve, 
the sub-occipital nerve, and the internal branches of 
the posterior divisions of the cervical nerves. 

BlVENTER CERVICIS. 

Origin. 

From the transverse processes of the three or four 
upper dorsal vertebrae. 
Insertion. 

Into the occipital bone, internal to the attachment 
of the complexus muscle. 
Nervous supply. 

From the same sources as the complexus. 
This muscle is often described as a fasciculus of the com- 
plexus muscle. 

Obliquus Capitis Superior. 
Origin. 

From the extremity of the transverse process of the 
atlas. 
Insertion. 

Into the occipital bone, between l_ A e curved lines on 
its inferior surface and external to the point of inser- 
tion of the complexus muscle. 
Nervous supply. 

Posterior branch of the sub-occipital nerve. 

Obliquus Capitis Inferior. 
Origin. 

From the spinous process of the axis. 
Insertion. 

Into the extremity of the transverse process of the 
atlas. 
Nervous supply. 

From two sources, viz., a branch of the sub-occipital 
and one from the great occipital nerve. 

Rectus Capitis Posticus Major. 
Origin. 

From the spinous process of the axis. 



MUSCLES OF THE NECK. 2 2$ 

Insertion. 

Into the inferior curved line of the occipital bone. 
Nervous supply. 

Posterior branch of the sub-occipital nerve. 

Rectus Capitus Posticus Minor, 
Origin. 

From the tubercle on the posterior arch of the atlas. 

Insertion. 

By fleshy fibres, into the occipital bone between the 
inferior curved line and the foramen magnum. 
Nervous supply. 

Posterior branch of the sub-occipital nerve. 

PALATE GROUP. 

(5 muscles). 
Tensor Palati. 
Origin. 

1. From the scaphoid fossa. 

2. From the adjoining portions of the sphenoid bone. 

3. From the cartilaginous portion of the Eustachian 
tube. 

Insertion. 

Into the anterior surface of the soft palate, after 
winding around the hamular process of the sphenoid 
bone. 
Nervous supply. 

A branch from the Otic ganglion. 

Levator Palati. 

Origin. 

From the apex of the petrous portion of the tempo- 
ral bone and the cartilaginous portion of the Eustach- 
ian tube. 
Insertion. 

Into the posterior surface of the soft palate, where 
its fibres blend with those of the opposite side. 
Nervous supply, 

A branch of the facial or 7th cranial nerve, through 
the vidian nerve. 
Palato-Glossus. 
Origin. 

From the anterior surface of the soft palate, on each 
side of the uvula. 



226 MYOLOGY. 

Insertion. 

Into the side and dorsum of the tongue, where it 
blends with the fibres of the stylo-glossus muscle. 
Nervous supply. 

Palatine branches of Meckel's ganglion. 

Palato-Pharyngeus. 
Origin. 

From the soft palate, by fibres connected with those 
of the opposite side. 
Insertion. 

After uniting with the stylo-pharyngeus muscle, it is 
inserted into the posterior edge of the thyroid carti- 
lage and the lateral walls of the pharynx. 
Nervous supply. 

Palatine branches of Meckel's ganglion. 
Azygos Uvulae. 
Origin. 

From the nasal spine of the palate bone. 
Insertion. 

Into the uvula and the tendinous aponeurosis of the 
soft palate. 
Nervous supply. 

A branch of the facial or 7th cranial nerve. 

MUSCLES OF THE PHARYNX. 

Inferior Constrictor. 
Origin. 

1. From the cricoid cartilage. 

2. From the oblique line on the thyroid cartilage 
and the cartilaginous surface behind it. 

3. From the inferior cornu of the thyroid cartilage. 
Insertion. 

Into the posterior median fibrous raphe of the 
pharynx, blending, in the middle line, with that of 
the opposite side. 
Nervous supply. 

By three sources, viz., the glossopharyngeal, the 
external laryngeal and the recurrent laryngeal nerves. 

Middle Constrictor. 
Origin. 

From the body and the cornua of the hyoid bone 
and from the stylo-hyoid ligament. 



ACTION OF MUSCLES OF NECK. 2 2J 

Insertion. 

Into the median raphe of the pharynx, and, by a few- 
fibres into the basilar process of the occipital bone. 
Nervous supply. 

The glosso-pharyngeal nerve and the pharyngeal 
plexus. 

Superior Constrictor. 

Origin, 

1. From the internal pterygoid plate (lower third) 
and from the palate bone. 

2. From the pterygo-maxillary ligament. 

3. From the aponeurosis, arising from the petrous 
portion of temporal bone. 

4. From the posterior part of the alveolar process of 
the inferior maxillary bone, above the mylo-hyoid ridge. 

5. From the base of the tongue. 
Insertion. 

Into the median tendinous raphe of the pharynx 
and the basilar process of the occipital bone. 
Nervous supply. 

The glosso-pharyngeal nerve and the pharyngeal 
plexus. 

Action of the Various Groups of Muscles of the Neck. 

The superficial layer of muscles assist in depression of the 
head, inclination of the head to one side, depression of the lower 
jaw, §jad, through the platysma myoides, in the expression of 
melancholy. 

The infra-hyoid group of muscles act as depressors of the 
larynx after it has been raised during the act of deglutition. 
They also act as tensors of the cervical fascia. 

The supra or genio-hyoid group of muscles are important 
agents in the act of deglutition, since, by them, the hyoid bone is 
raised, and with it, the larynx, trachea, pharynx and oesophagus ; 
the superior opening of the larynx is closed, and the bolus of food 
is controlled by the numerous movements of the tongue. In 
case liquids be swallowed by suction, the tongue is given a proper 
longitudinal concavity, by the hyoglossus muscle, to afford a chan- 
nel for the fluid, after the vacuum in the mouth has been created. 

The stylo-hyoid group of muscles act upon the pharynx and 
the tongue. During their contraction, the pharynx is opened and 
ividened for the entrance of food during deglutition, and the base 
of the tongue is drawn backwards and upwards over the elevated 



228 MYOLOGY. 

larynx, thus closing the superior opening of the larynx and pre- 
venting the entrance of food into its interior. 

The prevertebral group of muscles flex the head, by the action 
of the recti capitis antici muscles ; they also flex the cervical 
portion of the spinal column, by means of the longi colli muscles, 
and they rotate the head upon the spinal axis, when the recti 
capitis antici and laterales are in action. The spinal column, in 
the cervical region, may be also bent to 07ie side and flexed, when 
the three scaleni muscles of either side act independently, provided 
the trunk be a fixed point, or they may assist in preserving it in 
an erect posture when acting in unison. These muscles however 
become, during inspiration, powerful elevators of the first and 
second ribs, as in this case, the spinal column becomes the fixed 
point of resistance, and the thorax is therefore acted upon. 

The posterior cervical group of muscles serve mainly the pur- 
pose of controlling the erect position of the upper portion of the 
spine and maintaining the poise of the head. With the excep- 
tion of the rectus capitis major and the inferior oblique muscles, 
which produce rotation of the head, the others either tend to 
incline the head to one side, when acting singly, or to draw it 
backwards, when the pairs act simultaneously. 

We may say then in summary of the muscles acting upon the 
head, or upon the cervical portion of the spinal column and thus 
indirectly affecting the head, that, each pair of muscles produce 
a different effect when acting singly or in unison. 

Thus the head may be simply inclined to one side by the pla- 
tysma, sterno-mastoid, splenius, complexus, and the scaleni, when 
acting singly, or flexion or extension of the head will be produced, 
if the muscles act in pairs. 

The head may be flexed upon the neck by the recti capitis 
antici majores and minores, and the chin approximated to the 
chest by the longi colli and sterno-mastoid muscles, which cause 
flexion of the cervical portion of the spine ; but to accomplish 
these effects the muscles of each side must contract simultane- 
ously. The muscles included in the supra and infra-hyoid groups 
may also greatly assist in flexion of the cervical portion of the spine. 

The head may be rotated by the movements of the atlas upon 
the axis, produced chiefly by the action of the recti capitis antici 
and laterales, the recti capitis postici majores and the obliqui su- 
periores, althoug others muscles may produce rotation of the head 
as an indirect rather than a direct effect of their contraction. 

The head is drawn backwards by the simultaneous action of 
the following pairs of muscles, viz., the recti capiti postici majores 



ACTION OF MUSCLES OF NECK. 22 3 

et minores, complexi, obliqui superiores, splenii capitis et colli, 
trapezii and trachelo-mastoidei. 

The sixth or palate group of muscles are essentially muscles of 
deglutition. By their action the palate is raised and made tense, 
the opening of the posterior nares is protected from regurgitation 
of food, the tongue and fauces are made to assist in expelling the 
bolus of food into the pharynx and the orifice between the pillars 
of the fauces is diminished in size, thus also assisting in the re- 
tention of the food within the proper channels. 

The constrictor muscles of the pharynx (the seventh group,) are 
also muscles of deglutition. They act subsequently to the action 
of the elevators of the hyoid bone and the larynx. They are also 
important muscles in singing, since they tend to modulate the 
high notes. 

The eighth group of muscles, the laryngeal group, consist of 
seven pairs and one single muscle. Of these, four pairs and one 
single muscle (the arytenoideus) act upon the vocal cords and 
control phonation. The action of these muscles is as follows : 

Muscles which stretch the vocal cords. . . .The cricothyroid muscles. 

44 44 relax " " " The thyro-arytenoid muscles. 

44 " open the glottis The cricoarytenoid postici. 

" " close the glottis. The j ™o™ D LA '' ERALES - 

The three muscles which are attached to the epiglottis act as 
follows : 

Muscle compressing the superior opening of f ArYTENO-EPIGLOTTIDEUS superoris. 
the larynx during deglutition ( 

Muscle .depressing the epiglottis during the ( Thyro . epiglottideus . 

act of deglutition / 

Muscle compressing the sacculus laryngis. . \ Aryteno-epiglottideus inferoris. 

The origin and insertion of the muscles of the larynx as well 
as their nervous supply, which have been omitted in this chapter, 
will be found fully described in subsequent pages of this work, 
since they can only be clearly understood by a previous descrip- 
tion of that organ. 

NERVOUS SUPPLY. 
In the following pages will be found the muscles of the neck 
tabulated with their nervous supply indicated by lines running 
from each of the muscles to the source of its motor function. 
These tables also show the number of muscles supplied by each 
nerve, as well as the number of sources, from which each muscle 
is supplied, in case more than one motor nerve to the muscle 
exists. 



230 

TABLE OF NERVE 



Name of Nerve. 
Spinal accessory. . I 




Total 27 muscles. 
Deduct muscles 
with two sour- 
ces of nervous 

su pp!y 5 



MYOLOGY. 

SUPPLY TO THE MUSCLES OF 
THE NECK. 

Name of Muscle. Name of Group, 

Platysma myoides 1 Superficial lateral 

Sterno-cleido-mastoid ) group (2) 



Infra hyoid group (4) 



Supra hyoid group (6) 



Sterno-hyoid 

Sterno-thyroid 

Omo-hyoid.. 

Thyro-hyoid 

Anterior belly of digastric. 

Mylo-hyoid 

Genio-hyoid 

Genio-hyo-glossus 

Hyo-glossus 

Lingualis 

Posterior belly of digastric. 

Stylo-hyoid 

Stylo-glossus 

Stylo-pharyngeus 

Longus colli 

Rectus capitis anticus major 

Rectus capitis anticus minor 

Rectus capitis anticus later- 1 „ _, , , 

a jj s> r Frevertebral group (7) 

Scalenus anticus 



Stylo-hyoid ox sub- 
maxillary group (3) 



Scalenus medius.. 
Scalenus posticus. 



Total, 22 



Total 22 muscles. 



MUSCLES OF THE NECK. 



231 



Name of Nerve. 

External posterior 
branches of cer- 
vical nerves 4 

Internal posterior 
branches of cer- 
vical nerves 4 

Vidian nerve 2 

Meckel's ganglion. .2 
Otic ganglion 1 

Pharyngeal plexus. 3 
Glossopharyngeal. 3 




Superior laryngeal. 2>\ 



Inferior laryngeal. .6 



Deduct muscles 
supplied from 
two sources. . . 



28 

4 
24 



(Table continued.) 
Name of Muscle. 
Splenius capitis 




Trachelo-mastoid 

Complexus 

Biventer cervicis 

Obliquus superior 

Obliquus inferior 

Rectus capit. posticus major 

Rectus capit. posticus minor 
Tensor palati 



Name of Group. 



Posterior cervical 
group (8) 



Levator palati 

Palato-glossus 

Palato-pharyngeus 

\ Azygos uvulae. 

Superior constrictor 

Middle constrictor 

Inferior constrictor 

Crico-thyroid 

Aryteno-epiglottideus super. 
Aryteno-epiglottideus infer. 

Thyro-arytenoid 

Crico-arytenoid posticus. . . 
Crico-arytenoid lateralis. . . 
Arytenoideus 



■Muscles of palate. (5) 



Muscles of pha- 
rynx (3) 



- Muscles of larynx. (8) 



Total, 24 



TRIANGLES OF THE NECK. 

That portion of the neck extending from the median line, in 
front, to the anterior border of the trapezius muscle, behind, is 
divided, upon each side, into two great triangles by the sterno- 
mastoid muscles. The triangle, which lies in front of the sterno- 
mastoid muscle, is termed the anterior triangle of the neck, while 
the one lying behind that muscle is termed the posterior triangle 
of the neck. These two large triangles are subdivided bv the 



23^ 



MYOLOGY. 



omo-hyoid mnscle, and the anterior triangle is again subdivided by 
the two bellies of the digastric muscle, thus forming five distinct 
triangles, which are specially named. 

Diagram of the Triangles of the Neck. 

Lower Jaw. 





^^ 


/ 




\- 


>o I 


-i 


Hyoid bone. 




\% 1 




n 


w 


\ J/ 


Iff 


5' 

3 




\ / 




5' 
a 




<A\. 








V 






' V ^ 







Clavicle. 

The preceding diagram illustrates these surgical triangles, 
formed by the muscles of the neck. They are of interest, since 
their boundaries mark spaces, in which important vessels and 
nerves are contained. They have been named as follows : 
I. The SUBMAXILLARY triangle. 
II. " SUPERIOR CAROTID " 

III. " INFERIOR CAROTID " 

IV. " OCCIPITAL " 
V. " SUBCLAVIAN " 

Their boundaries are thus described : 

Inferior Carotid Triangle. 

In front, by the median line of the neck. 

Behind, by the anterior margin of the sterno-mastoid muscle. 

Above, by the anterior border of the omo-hyoid muscle. 

The floor is formed by the longus colli and scalenus anticus muscles. 

Superior Carotid Triangle. 

Above, by the posterior belly of the digastric muscle. 

Behind, by the sterno-mastoid muscle. 

Below, by the anterior belly of the omo-hyoid muscle. 

f Hyo-glossus. 
The floor is formed by the J Thyro-hyoid. 

following muscles. j Inferior constrictor. 

\ Superior constrictor. 

Submaxillary Triangle. 

Above, by the lower border of the jaw, the parotid gland and the mastoid process 
Behind, by the posterior belly of the digastric and the stylo-hyoid muscles. 
In front, by the middle line of the neck. 



The floor is formed by the j ^T ^f 7 ° f di S astric « 
following muscles: j ^ylo-hyoid. 

° ( Hyo-glossus, 



TRIANGLES OF THE NECK. 233 

Occipital Triangle. 

In front, by the posterior margin of the sterno-mastoid muscle. 

Behind, by the trapezius muscle. 

Below, by the posterior belly of the omo-hyoid muscle. 

f Splenius. 
The floor is formed by the J Levator anguli scapulae, 
following muscles : | Scalenus medius. 

(Scalenus posticus. 

Subclavian Triangle. 

Above, by the posterior belly of the omo-hyoid muscle. 

Below, by the clavicle. 

In front, by the posterior margin of the sterno-mastoid muscle. 

The contents and relations of these triangles will be consid- 
ered under the chapters descriptive of the vessels of the head and 
neck. 

SURGICAL RELATIONS OF SPECIAL MUSCLES OF 
THE HEAD AND NECK. 

Between the internal and external pterygoid muscles, lie the 
internal maxillary artery and vein ; and the dental and gustatory 
nerves separate the internal pterygoid muscle from the ramus of 
the inferior maxillary bone. 

Across the buccinator muscle, run the facial artery and vein ; 
and this muscle is perforated by Steno's duct, which opens into 
the mouth opposite to the 2nd molar tooth of the upper jaw. 

The hypoglossal nerve passes between the fibres of the genio- 
hyo-glossus. The gustatory nerve crosses the upper margin of the 
hyo-glossus, the lingual nerve crosses its middle portion, while, 
beneath it, lies the lingual artery. 

The external carotid artery is separated from the internal car- 
otid artery and the jugular vein by the stylo-pharyngeus and stylo- 
glossus muscles, and the glossopharyngeal nerve lies upon the 
outer side of the same muscle. 

The sterno-mastoid muscle serves as a guide to the common 
carotid artery, as its inner border lies in close relation to it, and 
the stemo-hyoid and sterno-thyroid muscles, which also lie in close 
relation to this large vessel, require to be drawn towards the 
median line of the neck in case its ligature is demanded. 

The scalenus anticus muscle lies immediately in front of the 
second portion of the subclavian artery, and the brachial plexus 
Anterior to the muscle but in close relation to it, lies also the 
phrenic nerve, and the subclavian vein. 

The cervical plexus of nerves lies upon the levator anguli scap- 
ulae and the scalenus medius muscles and is covered in by the 
sterno-mastoid muscle. 



234 



MYOLOGY. 



The anterior jugular veins pass underneath the ster no-mast oid 
muscle, at its lower portion, while the external jugular vein crosses 
in front of it, at its upper portion, and lies parallel to its posterior 
border, in its course down the neck. 

The posterior external jugular vein lies between the splenius 
and the trapezius muscles. 

The longus colli muscles are in relation, posteriorly, on each 
side, with the first portion of the subclavian artery, while the 
sternal origin of the sterno-mastoid and the sterno-hyoid and 
sterno-thyroid muscles lie in relation anteriorly with the same 
portion of that artery. 

THE MECHANISM OF THE ACT OF DEGLUTITION. 

The act of deglutition requires for its performances not only 
the cooperation of a large number of those muscles, included in the 
various groups in the region of the head and neck, but it requires, 
in addition, that these muscular contractions be performed in a 
direct order of succession and at a time when their action will 
directly and properly affect the bolus of food. 

The act of deglutition has therefore been divided, for con- 
venience of description, into three distinct stages, as follows : 

1st period, comprising the passage of the bolus to the isth- 
mus of the fauces. 

2nd " comprising the passage of the bolus through the 
pharynx into the oesophagus. 

3rd " comprising the passage of the bolus through the 
oesophagus. 

In the first period, the muscles under the control of the will, 
viz., those of the tongue, lower jaw and soft palate become im- 
portant factors. 

The mouth is first closed to assist the tongue in its action, 
since its attachments to the lower jaw impair its movements 
when the mouth is open. The tongue now becomes increased 
in width, save when the suction of liquids is performed, and the 
bolus is pressed by the tongue against the hard palate and slid 
backwards until it touches the soft palate. The tensor palati 
and the palato-glossus muscles now contract, and thus a partial 
resistance is made to further progress backwards of the bolus. 

In the second period the control of the bolus is lost. A series 
of rapid muscular contractions of a reflex type ensue, which drive 
the bolus through the fauces and pharynx till it reaches the 
oesophagus. 



MUSCLES OF THE NECK. 



235 



The larynx becomes suddenly raised by the mylo-hyoid, genio- 
hyoid, stylo-hyoid, thyro-hyoid, genio-hyo-glossus, and the ante- 
rior belly of the digastric muscles; and the pharynx becomes si- 
multaneously widened by the approximation of its two extremities. 

The soft palate is raised, by the action of the levator palati 
muscle and by the pressure of the bolus ; and the azygos uvulae is 
grasped by the contraction of the superior constrictor muscle of 
the pharynx, which thus prevents the regurgitation of food into 
the nares. 

The isthmus of the fauces is subsequently closed behind the 
bolus, as it passes that point ; and, by the close approximation of 
the palato-pharyngeus muscles, the nares and buccal cavity are 
further protected from regurgitation. 

The larynx is protected from the entrance of the food, by an 
adaptation of the tongue and epiglottis to its superior opening; 
and also by the approximation of the vocal cords and compression 
of the superior opening, through the action of the crico-arytenoid 
lateralis, the aryteno-epiglottideus superior, and the arytenoid 
muscles. 

The successive contraction of the three constrictor muscles of 
the pharynx drives the bolus, therefore, into the oesophagus, since 
all other means of exit from its cavity are closed. 

The third period is characterized by contractions of the longi- 
tudinal muscular fibres of the oesophagus, which constantly slips 
its mucous membrane above the bolus, and by subsequent con- 
traction of its circular fibres, in a peristaltic action similar to that 
perceived in the lower portions of the alimentary canal. 



236 MYOLOGY, 

MUSCLES OF THE TRUNK. 

The muscles of the trunk may be divided as follows : 

A. Muscles of the Abdomen. 

B. Muscles of the Thorax. 

C. Muscles of the Back. 

D. Muscles of the Perineum. 

Each of these regions will be considered separately. 

A. 

MUSCLES OF THE ABDQMEN. 

The muscles which form the antero-lateral wall of the abdomen 
are six in number in the male sex, and five in number in the 
female. They may be thus divided : 

Those between the linea alba and the line a \ Rectus abdominis. 

semilunaris . . (2) \ Pyramidalis. (Sometimes wanting.) 

("Obliquus abdominis externus. 
Those between the linea semilunaris and the] Obliquus abdominis internus. 

vertebral column . . (4) j Cremaster (in males only.) 

[Transversalis abdominis. 

ORIGIN AND INSERTION. 

Rectus Abdominis. 
Origin. 

Arises by two tendons ; one being attached to the 
crest of the pubes, and the other to a ligament cov- 
ering the symphysis pubis. 
Insertion. 

1. Into the ensiform cartilage and the costo-xiphoid 
ligaments. 

2. Into the cartilage of the 5th, 6th and 7th ribs. 
This muscle is intersected by transverse tendinous slips, 

varying from three to five in number, which are adherent, ante- 
riorly, to its sheath. 
Nervous supply. 

The lower intercostal nerves. 

Pyramidalis. 
Origin. 

From the anterior portion of the pubes and the an- 
terior pubic ligament. 

Insertion. 

Into the linea alba, midway between the umbilicus 

and the os-pubis. 



MUSCLES OF THE A B DOME AT. 



237 



Nervous supply. 

The iliohypogastric nerve. 

Obliquus Abdominis Externus. (External or descending 
oblique). 
Origin. 

By eight fleshy digitations, from the external sur- 
face and lower borders of the lower eight ribs. 
Insertion. 

1. By fleshy fibres, into the anterior half of the 
outer lip of the crest of the ilium. 

2. Into the whole length of the linea alba, by means 
of an aponeurosis. 

3. By Poupart's and Gimbernat's ligaments, into the 
spine of the pubes and into about one inch of the 
pectineal line. 

Nervous supply. 

The lower intercostal nerves. 
Action. 

To depress the ribs, to, compress the viscera, to 
raise the pelvis if the thorax be fixed, or to flex the 
spine, if the pelvis be made a fixed point. 
The so-called " triangular ligament " is a reflection of fibres 
from Gimbernat's ligament to the linea alba. 
Obliquus Abdominis Internus. 
Origin. 

1. From the external half of Poupart's ligament. 

2. From the anterior two-thirds of the middle lip 
of the crest of the ilium. 

3. From the posterior layer of the fascia lumborum. 
Insertion. 

1. By fleshy fibres, into the lower borders of the four 
* inferior costal cartilages. 

2. Into the linea semi-lunaris and the linea alba. 

3. Into the body of the pubes and the pectineal line, 
in common with the fibres of the transversalis muscle, 
thus forming the so-called " conjoined tendon' 

Nervous supply. 

Ilio-hypogastric and ilio-inguinal nerves 
Transversalis Abdominis. 
Origin. 

1. From the external third of Poupart's ligament. 

2. From the anterior three-fourths of the internal 
lip of the crest of the ilium. 



2 3 8 



MYOLOGY. 



3. From the fascia lumborum. 

4. From the inner surfaces of the cartilages of the 
lower six ribs. 

Insertion. 

1. Into the linea semi-lunaris and the linea alba, 

after joining with the posterior lamella of the apon- 
eurosis of the internal oblique muscle. 

2. Into the crest of the pubes, the pubic end of 
Poupart's ligament, and the linea pectinea, (thus help- 
ing to form the conjoined tendon?) 

3. The internal portion of the muscle passes behind 
. and beneath the spermatic cord, and is inserted subse- 
quently into Poupart's ligament. 

Nervous supply. 

Lower intercostal nerves. 

Cremaster. 

1. From the middle portion of Poupart's ligament* 

2. Behind the pubic insertion of that ligament. 

Insertion. 

By successive loops, the spermatic cord is surround- 
ed as well as the testicle and the tunica vaginalis. 
Nervous supply. 

The genito-crural nerve. 
Action. 

To suspend the testicle. 

ACTION OF THE ABDOMINAL MUSCLES. 

The abdominal muscles, when the pelvis and thorax are made 
fixed points, exert a powerful influence, during their contraction, 
upon the abdominal viscera, and in these acts the diaphragm be- 
comes also a powerful adjunct. 

Thus, in the act of vomiting, and in the expulsion of the foetus 
from the womb, the act of defecation, or the evacuation of the 
urine from the bladder, (in cases where any obstruction to the free 
exit of their contents exists), a long breath is usually taken before 
the abdominal muscles contract ; since, by so doing, the dia- 
phragm presents a state of tension eminently calculated to direct 
the entire force of their contraction upon the viscera. 

They also assist in expiration, by depressing the lower part of 
the thorax, when the spine is made a fixed point ; and, in cases 
where the spine is relaxed, they tend to flex the thorax upon the 
pelvis, if both sides act simultaneously, or, if not, they produce a 
lateral displacement of the thorax, with a partial rotation of the 
trunk towards the side opposite to the muscles in contraction. 



MUSCLES OF THE ABDOMEN 1 . 



239 



The abdominal muscles also assist greatly in drawing the pel- 
vis upwards, when the thorax becomes a fixed point, as is illus- 
trated in the act of climbing. 

The recti muscles are depressors of the thorax and serve to 
flex the spinal column, if the pelvis be fixed ; or, if the thorax be 
made the point of resistance, the pelvis may, by these muscles, be 
flexed upon the vertebral column. 

The pyramidalis muscle, though often wanting, tends, when 
present, to act as a tensor of the linea alba. 

NERVOUS SUPPLY OF THE ABDOMINAL MUSCLES. 



Name of Nerve. 



Lower intercostal 
nerves. 



Ilio-hypogastric. 

Ilio-inguinal. 

Genito-crural 




Name of Muscle. 
Rectus abdominis. 
Pyramidalis. 



Obliquus abdom. externus. 

Obliquus abdom. internus. 

Transversalis abdominis. 
Cremaster. 



Group. 

Internal to lined, 
semilunaris. 



^External to the 
linea semilu- 
naris. 



DIRECTION OF THE FIBRES OF EACH MUSCLE. 

As the abdominal walls demand a great power of resistance to 
internal pressure, we find the muscular layers arranged so as to 
prevent a possible separation of the various fibres, which would 
afford an opportunity for protrusion of viscera. 

The fibres of each of the abdominal muscles are therefore 
directed differently, as is shown in the following: 

External oblique muscle downwards and inwards. 

Internal oblique muscle upwards and inwards. 

Transversalis abdominis muscle horizontally. 

Rectus abdominis muscle upwards. 

Pyramidalis muscle upwards. 

POINTS OF SURGICAL INTEREST PERTAINING TO 
THE ABDOMINAL MUSCLES. 

The aponeurotic tendon of the internal oblique muscle o( the 
abdomen deserves special notice. 

At the outer margin of the rectus abdominis muscle, this 
aponeurosis, for the upper three-fourths of its extent, splits into 
two lamellae, one of which passes in front and the other behind the 



?40 



MYOLOGY. 



muscle, thus enclosing it in a kind of sheath, and, reuniting on the 
inner border of this muscle, the tendon becomes continuous with 
its fellow of the opposite side, and assists in forming the linea 
alba. The anterior layer of this aponeurosis becomes blended, in 
its passage over the rectus muscle, with the tendon of the external 
oblique muscle ; and the posterior layer, during its passage behind 
the rectus muscle, also becomes continuous with the tendinous 
aponeurosis of the transversalis abdominis muscle. 

In the lower fourth of the rectus muscle, however, the aponeu- 
rosis of the internal oblique does not separate into lamellae, but 
passes, with the aponeurosis of the transversalis abdominis, en- 
tirely in front of that muscle. 

Of these muscles the following prominent points also deserve 
special mention, as the parts have important surgical relations to 
hernial protrusions. 

A. Poupart's Ligament. 

This ligament is formed by the lower fibres of the 
aponeurosis of the external oblique muscle, and ex- 
tends from the anterior superior spine of the ilium to 
the spine of the pubis. 

B. Gimbernat's Ligament. 

This ligament is a reflection of fibres derived from 
Pouparf s ligament, backwards and inwards, to the pec- 
tineal line. 

C. The Pillars of the External Ring. 

The external and the internal pillars of the external 
abdominal ring are formed by the aponeurosis of the 
external oblique muscle. They enclose an opening, 
called the exter?ial abdominal ring, one-half to three- 
quarters of an inch in length, for the transmission of 
the spermatic cord, in the male, and the round liga- 
ment, in the female. 

D. Triangular Ligament. 

This ligament is formed by fibres, reflected from 
Gimbernai 's ligament, which extend behind the inter- 
nal pillar of the external abdominal ring, to the linea 
alba. 

E. The Intercolumnar Fascia. 

This is a prolongation of the spermatic fascia, which 
extends between the two pillars of the external 
abdominal ring, and which renders the opening of the 
external abdominal ring almost square in shape. 



MUSCLES OF THE ABDOMEN. 



241 



F. The Inguinal Canal. 

This canal is one and a half inches in length and 
extends from the internal abdominal ring to the exter- 
nal abdominal ring. It has the following boundaries : 



In front. (5 structures). 



Behind, (5 structures). 



fSkin. 

J Superficial fascia (two layers). 
1 External oblique muscle, for its entire length. 
(_ Internal oblique muscle, for its outer third. 
f Conjoined tendon, of the internal oblique 
and transversalis muscles. 

Transversalis fascia. 

Triangular ligament. 

Sub peritoneal tissue and fat. 

Peritoneum. 

A , , , , ( Fibres of internal oblique muscle, 

Above. (2 structures). . . . \ ~ M r ; ,. 4 ,j . . ' , 

v ' ( b ibres of transversalis abdominis muscle. 

D 7 ,. , v \ Poupart's ligament. 

Below. (2 structures) \ T ' {? c 

v ' {\. ransversalis fascia. 

This canal lies parallel with Pouparfs ligament, and is directed 
downwards and inwards. Its extremities are named respectively 
the internal abdominal ring and the external abdominal ring. It 
transmits the spermatic cord, in the male, and the round ligament, 
in the female. 

G. The Femoral Ring. 

This opening is oval in shape, is one half of an inch 
in breadth, and is situated underneath Poupart's liga- 
ment, internal to the femoral vessels. It has the fol- 
lowing boundaries : 

Above, (.structures) \*%%£^ 

{ Pubic bone, 
z, , , N J Pectineus muscle. 

Below. (4 structures) ^ Iliac fascia . 

[_ Pubic portion of fascia lata, 
j" Gimbernat's ligament. 

T . J7 , . » J Conjoined tendon. 

Internally. (4 structures) . \ ^ crural arch- 

\ Transversalis fascia. 

Externally. (2 structures). «( Femoral vein and septum. 

From the spine of the pnbes outwards, we find, in the normal 
condition, the following structures in this order: 

1. Gimbemaf s ligament. 

2. Femoral opening. 

3. Femoral vein. 

4. Femoral artery. 

5. Anterior crural nerve. 

The term G. O. V. A. N. (the name of a town in Scotland,) 



242 MYOLOGY. 

may assist the memory by representing through its five letters 
the prominent italicised parts, in their order. 

H. The Femoral Canal. 

This canal is one-half of an inch in lengthy and ex- 
tends from the femoral ring to the upper part of the 
saphenous opening, in the thigh. It has the following 
boundaries : 

( Poupart's ligament. 
In front. (3 structures) .. . < Fascia transversalis. 

( Falciform process of tne fascia lata. 

Behind. (2 structures). . . . j ^/^^ of fasda lata> 

r, . ,, / v i Femoral vein. 

Externally. (2 structures), -j Femoral geptum _ 

f Fascia transversalis. 
Internally. (4 structures) . j ^berS's ligament. 
[Deep crural arch. 

This canal is closed, at its upper opening, (the femoral ring) by 
a fibrous septum called the septum crurale, which is protruded, 
therefore, as a covering to all hernial tumors in this region ; and, 
at its lower opening, this canal is also closed by a fascia, perforated 
by veins and called, for that reason, the cribriform fascia. 

Coverings of Inguinal and Femoral Hernia. 

In connection with the muscles of the abdomen, the various 
coverings in which hernial protrusions are encased may properly 
be considered. 

In the INGUINAL REGION, abnormal inguinal protusions of ab- 
dominal viscera or omentum may escape either indirectly, in 
which case they enter at the internal ring and pass through the 
whole length of the inguinal canal before they escape at the ex- 
ternal abdominal ring; or directly, in which case the abdominal 
walls are directly perforated behind the external abdominal ring, 
and, in consequence, the hernial protusion fails to enter either 
the internal ring or the inguinal canal. 

In both of these varieties, every hernial protusion starts with 
two coverings before it enters the abdominal wall. These two 
coverings are the peritoneum and the sub-serous connective tissue. 

When the indirect variety enters at the internal abdominal 
ring, it becomes invested with a third covering, viz., the infun- 
dibuliform process of the transversalis fascia, which is prolonged 
from this point around the cord and the testicle. Within the in- 
guinal canal, the cremaster muscle is next acquired as its fourth 
layer. As it escapes from the external abdominal ring, the fascia 



MUSCLES OF THE ABDOMEN, 243 

covering that opening, viz., the intercolumnar fascia becomes 
spread out upon the hernial sac as a fifth covering, and the two 
layers of the superficial fascia of the abdomen and the skin com- 
plete the eight layers, which must be divided to reach the cavity 
of the sac. 

In direct inguinal hernia, the sac starts with the same two 
coverings, viz., the peritoneum and the sub-peritoneal tissue. Since 
it does not enter the internal ring, it receives the transversalis 
fascia, without any specially designated portion of that tissue, 
as was the case in the indirect variety. As it does not enter the 
inguinal canal, it does not recieve the cremaster muscle as a cov- 
ering, but it acquires in its place, as a fourth layer, the conjoined 
tendon which lies behind the external abdominal ring and thus 
protects this part which would otherwise be weak. The hernial 
protrusion now escapes from the external ring, acquiring, as the 
indirect variety did, the intercolumnar fascia for its fifth lay$r, 
and, with the two layers of the superficial fascia of the abdomen 
and its integument, the sum total of its coverings tallies with that 
of the indirect variety of hernia, viz., eight. 

In the FEMORAL REGION, the sac starts from the same original 
coverings, viz., the peritoneum and the sub-peritoneal tissue. At 
the femoral ring, it acquires, as a covering, the septum crurale 
which opposes its exit from the abdomen and which becomes ex- 
panded over the surface of the tumor as it passes through that 
opening. 

As it traverses the femoral canal, the tumor becomes invested 
with a fourth layer, viz., the crural sheath, in which the femoral 
vessels are enclosed. 

At the saphenous opening, the cribriform fascia, which encloses 
that orifice, is acquired as a fifth layer ; and the two external in- 
vestments which remain consist of one layer only of superficial 
fascia and the integument of the upper portion of the thigh. 

In recapitulation, we may then state that both forms of ingui- 
nal hernia have eight layers of investments to the sac, while in the 
femoral variety only seven layers exist, since the deep layer of 
the superficial fascia of the thigh is continuous with the cribriform 
fascia, by which the saphenous opening is enclosed. 



244 



MYOLOGY. 



Diagram Illustrating the 7 Layers forming the Abdominal Wall in the 

Iliac Region. 



Intestines 
and Viscera. 



Integument. 

Superficial fascia (two layers.) 

External oblique muscle. 



■^^ Internal oblique muscle. 



^^ Transversalis muscle. 
^^ Fascia transversalis. 



i Peritoneum. 



This diagram is designed to show the coverings which suc- 
cessively are acquired by any hernial protrusions of omentum 
or intestine in the inguinal or iliac region. Although this diagram 
only represents seven layers as constituting the entire thickness 
of the abdominal wail, still the second layer will be perceived to 
consist of two separate portions. For this reason the coverings 
of inguinal hernia are usually described by anatomists as eight in 
number. 



MUSCLES OF THE THORAX. 245 

B. 

MUSCLES OF THE THORAX. 

The muscles of the thorax may be enumerated as follows : 

1. The External Intercostal muscles. 

2. The Internal Intercostal muscles. 

3. The Infracostales. 

4. The Levatores Costarum. 

5. The Triangularis Sterni. 

6. The Diaphragm. 

ORIGIN AND INSERTION. 

External Intercostales. 

There are eleven external intercostal muscles on each side of the 
body. They extend from the tubercle of the ribs, behind, to the 
commencement of the costal cartilages, in front. Their fibres are 
directed downwards and forwards. 
Origin. 

From the outer lip of a groove on the lower border 
of the rib. 
Insertion. 

Into the upper border of the rib next below. 
Nervous supply. 

The intercostal nerves. 

Internal Intercostales. 

These muscles extend from the sternum and the anterior ex- 
tremities of the false ribs, to the angle of the rib behind. Their 
fibres are directed downwards and backwards. They are eleven 
in number on each side. 

Origin. 

1. From the cartilages of the false and true ribs. 

2. From the inner lip of the groove on the lower 
border of each rib. 

Insertion. 

Into the upper border of the next rib below. 
Nervous supply. 

The intercostal nerves. 



Infra-costales 
Origin. 



From the inner surface of one rib. 



246 MYOLOGY. 

Insertion. 

Into the inner surfaces of the first, second and third 
ribs below. 
Nervous supply. 

The intercostal nerves. 
The direction of these muscles is usually parallel to that of the 
internal intercostals and they are most frequent on the lower ribs. 

Levatores Costarum, (twelve on each side). 
Origin. 

From the extremities of the transverse processes of 
dorsal vertebrae. 
Insertion. 

Into the upper rough surface of the rib next below, 
between its tubercle and its angle. 
Nervous supply. 

The intercostal nerves. 

The muscle for the 1st rib arises from the 7th cervical verte- 
bra. The muscle for the 12th rib arises from the nth dorsal 
vertebra. 

Frequently an inferior fasciculus of these muscles is carried to 
the second rib below the point of origin. 

Triangularis Sterni. 
Origin. 

1. From the lower part of the side of the sternum. 

2. From the inner surface of the ensiform cartilage. 

3. From the costal cartilages of the four lower true 
ribs. 

Insertion. 

Into the lower border and inner surface of the costal 
cartilages of the 2nd, 3rd, 4th and 5th ribs. 
Nervous supply. 

The intercostal nerves. 

Its lowest fibres are continuous with those of the transversalis 
abdominis muscle. 

Diaphragm. 

This muscle forms the dividing septum between the cavities 
of the thorax and abdomen. It is formed like a dome during its 
passive condition, as its central tendon is situated much higher 
than its circumferential attachment, but, during its contraction, 
it is more nearly a flat plane. 

It is the most important muscle of inspiration, and it is per 



MUSCLES OF THE THORAX. 



247 



forated by three openings for the passage of important structures. 
These openings, will be found described, in detail, under the head- 
ing " openings in the abdominal walls," in subsequent pages of 
this volume. 
Origin. 

In front, from the ensiform cartilage. 

Inner surface of costal cartilages. 
Bony portions of the seven lower ribs, 

(interdigitating with the transversalis 

abdominis.) 



Laterally, 
from the 



„ , . , C Ligamentum arcuatum externum. 
Insertion. 



a Ligamentum arcuatum internum. 
f Lumbar vertebrae. 



Into the central tendon of the diaphragm. 
Nervous supply. 

The phrenic nerve, a branch of the cervical plexus. 

The shortest fibres of this muscle arise from the ensiform 
appendix. The longest fibres of this muscle arise from the liga- 
mentum arcuatum externum and from the sides of the chest. 

The ligamentum arcuatum internum is a tendinous arch extend- 
ing across the psoas magnus muscle, on each side of the spinal 
column. It is connected to the bodies of the 1st and 2nd lumbar 
vertebrae, at its inner extremity, and to the transverse process, at 
its outer extremity. 

The ligamentum arcuatum externum is the thickened upper 
margin of the anterior lamella of the transversalis fascia, which 
arches across the quadratus lumborum muscle, on either side ; and 
which is attached, at its inner extremity, to the transverse pro- 
cess of the 2nd lumbar vertebra, and, at its outer extremity, to 
the apex and the lower margin of the last rib. 

ACTION OF THE MUSCLES OF THE THORAX. 

These muscles are chiefly aids in the acts of inspiration and 
of expiration. They are assisted, however, in these complex 
muscular efforts, by certain other muscles which have been classed 
under the respective heads of those of the upper extremities, 
back, neck, and abdomen. 

As the action of these muscles upon respiration is important, 
from a physiological point of view, and, as the auxiliary muscles 
often play a most important part in the complete performance o\ 
these acts, classified tables are appended of all the muscles which 



248 



MYOLOGY. 



Muscles of ordinary inspiration ■< 



prominently effect either inspiration or expiration, although some 
of these muscles have not yet been described in this volume. 

MUSCLES OF INSPIRATION. 

Diaphragm. 

Scalenus anticus. 

Scalenus medius. 

Scalenus posticus. 

External intercostals. 

Sternal portion of internal intercostals. 

xi Levatores costarum, 

~ ,. ... , ( Serratus posticus superior. 

Ordinary auxiliary muscles -j S terno-mastoid. 

f Levator anguli scapulae. 
Trapezius (superior portion,) 
Extraordinary auxiliary muscles. . . . \ Pectoralis minor. 

I Pectoralis major (inferior portion.) 
[_ Serratus magnus. 

All of these muscles tend to increase the capacity of the chest, 
when the thorax ceases to be the fixed point of resistance. They 
are therefore muscles of inspiration. 

MUSCLES OF EXPIRATION. 

{Osseous portion of the internal intercostals. 
Infra-cost ales. 
Transversalis abdominis. 
TObliquus abdominis externus. 
... . . ... Triangularis sterni. 

Auxiliary muscles in expiration.^ Qbliquus abdominis INTE rnus. 

[ Sacro-lumbalis. 

The muscles included in this table are capable«of directly dimin- 
ishing the capacity of the chest, and are therefore muscles of ex- 
piration. 

During inspiration, the vertical measurement of the cavity of 
the chest is increased from two to three inches, and the heart is 
drawn downwards by the diaphragm, on account of the attach- 
ment of the pericardium to its central tendon. 

The cavity of the thorax is diminished in its vertical diameter, 
during the passive condition of the diaphragm, or when the ab- 
dominal viscera are enlarged or distended ; hence the oppression 
felt in the chest after a full meal, or from distension of the stomach 
or intestines with gas. 

The diaphragm may, however, be an important agent in other 
acts than those of inspiration and expiration, since, in a state of 
contraction, it compresses the oesophageal opening of the stomach 
through its muscular fibres. It is therefore to be remembered that 
the cardiac end of the stomach is closed during inspiration, and thus 
the possibility of regurgitation of its contents from the pressure 
of the diaphragm is prevented. 



MUSCLES OF THE BACK. 



249 



In the acts of hiccough, crying, sobbing, laughing and snuffing 
of odoriferous effluvia, the diaphragm is the most important fac- 
tor, as its spasmodic and involuntary contractions produce those 
sudden and unexpected inspirations experienced in all of these 
five conditions. 

The external intercostal muscles raise the ribs and are there- 
fore muscles of inspiration. They are, however, assisted in this 
act by the levatores costarum and the sternal portion of the in- 
ternal intercostals. 

The external intercostals are wanting in the region of the costal 
cartilages, being attached only to the rib. 

The intercostal muscles can, however, elevate the ribs only 
after the first rib has been made a fixed point by the scaleni 
muscles, since their action is essentially from above downwards. 



NERVOUS SUPPLY TO THE MUSCLES OF THE 
THORAX. 

f External intercostals. 

Internal intercostals. 
The intercostal nerves supply^ Infra costales. 

Triangularis sterni. 
_ Levatores costarum. 

The phrenic nerve supplies . . \ Diaphragm. 



MUSCLES OF THE BACK. 
The muscles of the back consist of 21 pairs, and are arranged 
in five layers, as follows : 

Muscles of 1st or superficial layer.( 2 ) \ l^Smus dorsi. 



Muscles of 2nd layer. 



{Levator anguli scapula. 
Rhomboideus minor. 
Rhomboideus major. 

AT , , , , , N ( Serratus posticus superior. 

Muscles of 3rd layer (2) j Serratus posticus inferior . 

rTRACHELO-MASTOID. ) 

Cervicalis ascendens. >• iii neck. 
Transversalis COLLI. ) 
Accessorius. 

Muscles of 4th layer (9)^ Spinalis colli. 

Spinalis dorsi. J-in the back. 
longissmus dorsi. 
Sacro-lumbalis. 
^Erector spin/B. J- in the loins. 
SEMI-SPINAl is dorsi. 

Semi-spinalis colli. 

MULTIFIDUS SI'lVK 

R.0 r \ rORES SPINiE, 

SUPRA-SPIN M is. 

1 N rER-SPINALES. 

EX rENSOR COCCYGIS. 

In 11 k- ikans\ ERSALES. 



Muscles of the 5th layer (S)- 



250 MYOLOGY, 



Trapezius. 



ORIGIN AND INSERTION. 

SUPERFICIAL LAYER. 

(2 muscles.) 



1. From the ligamentum nuchse and the correspond- 
ing portion of the supra-spinous ligament. 

2. From the spinous processes of the 7th cervical 
and the 12th dorsal vertebrae. 

3. From the inner third of the superior curved line 
of the occipital bone. 

Insertio?t. 

1. Into the upper lip of the spine of scapula. 

2. Into the inner margin of the acromion process. 

3. Into the external third of the posterior border 
of the clavicle. 

Nervous supply. 

Spinal accessory nerve, or nth cranial, and the deep 
branches of the cervical plexus. 
The lower border of the trapezius muscle may be defined, upon 
the back of a living subject, by a line drawn from the spine of 
the scapula to the spine of the last dorsal vertebra. 

Latissimus Dorsi. 
Origin. 

1. From the spinous processes of the lower six dor- 
sal vertebrae and the supra-spinous ligament. 

2. From the spinous processes of the lumbar verte- 
brae and the sacrum. 

3. From the posterior third of the outer lip of the 
crest of the ilium. 

4. From the last four ribs, by fleshy digitations. 
Insertion. 

Into the bottom of the bicipital groove of the 
humerus. 
Nervous supply. 

The long sub-scapular nerve, from the brachial 
plexus. 
The upper border of the latissimus dorsi muscle may be de- 
fined, upon the back of a living subject, by a line drawn from the 
spine of the sixth dorsal vertebra in a horizontal direction over 
the inferior angle of the scapula. 



MUSCLES OF THE BACK. 25 I 

ACTION OF THE SUPERFICIAL LAYER. 

The action of these muscles is demanded in various move- 
ments of the head, scapula, and the humerus. If the head be 
made a fixed point, the trapezius muscle helps, through its upper 
fibres, to elevate the point of the shoulder, as in the acts of sup- 
porting weights, shrugging the shoulders, etc., while, by means 
of its middle and lower fibres, a partial rotation of the scapula 
upon the side of the chest is produced. When the shoulders are 
fixed, both of the trapezii muscles, if acting together, will draw 
the head directly backwards, or, if only one act, the head will be 
drawn towards the corresponding side. 

The latissimus dorsi, if the trunk be the fixed point, acts upon 
the arm and draws it downwards and backwards and subsequently 
rotates the arm inwards, as in the act of scratching the gluteal 
region. If this muscle acts in connection with the pectoralis 
major and the teres major muscles, the arm is adducted and ap- 
proximated to the chest wall. If the arms be made a fixed point, 
the latissimus dorsi muscle may assist in forcible inspiration by 
elevating the lower ribs (as is illustrated in the attitude assumed 
by asthmatic patients) ; or if it acts in connection with the pectoral 
and abdominal muscles, while the arms are made a point of resist- 
ance, the whole trv.nk may be drawn forward or upward, as is illus- 
trated in the acts of climbing or walking upon crutches. 

SECOND LAYER. 
(3 muscles.) 

Levator Anguli Scapulae. 
Origin, 

From the posterior tubercles of the transverse pro- 
cesses of the three or four upper cervical vertebrae. 
Insertion. 

Into the base of the scapula, from its spine to the 
superior angle. 
Nervous supply. 

The 5th cervical nerve and deep branches from the 
cervical plexus. 

Rhomboideus Minor. 
Origin, 

From the ligamentum nucha: and the spinous pro- 
cesses of the 7th cervical and the first dorsal vertebrae. 



2 $2 MYOLOGY. 

Insertion. 

Into the posterior edge of the scapula, between the 
two roots of its spinous process. 
Nervous supply. 

The 5 th cervical nerve. 

Rhomboideus Major. 

Origin. 

From the spinous processes of the four or five upper 
dorsal vertebrae. 

Insertion. 

Into the base of the scapula, between its spine and 
its inferior angle. 

Nervous supply. 

The 5th cervical nerve. 

The levator anguli scapulce raises the angle of the scapula, 
after it has been depressed by the trapezius; and, if the shoulder 
be a fixed point, it may tend to incline the neck to the corres- 
ponding side. 

The rhomboid muscles, by carrying the angle of the scapula 
backwards and upwards, produce a slight rotation of the scapula 
upon the side of the chest. If the shoulder be made a fixed 
point, these muscles will draw the scapula directly backwards 
towards the spinal column, and, in this act, they are assisted by 
the middle and the inferior fibres of the trapezius. 

Below the scapula, upon the back, near the 7th, 8th and 9th 
ribs, is a triangular space bounded by the trapezius, latissimus 
dorsi and the rhomboideus major muscles, where the lung can be 
auscultated without muscular intervention, save the intercostals. 
This space can be enlarged by stooping and throwing the arms 
forwards upon the chest, as is usually done when auscultation of 
the chest is performed. 

THIRD LAYER. 
(2 muscles.) 

ORIGIN AND INSERTION. 

Serratus Posticus Superior. 
Origin. 

1. From the ligamentum nuchae. 

2. From the spinous processes of 7th cervical and 1st 
2d and 3d dorsal vertebrae. 



MUSECLS OF THE BACK. 253 

Insertion. 

Into the 2d, 3d, 4th and 5th ribs beyond their 
angles. 

Nervous supply. 

External posterior branches of the cervical nerves. 

Serratus Posticus Inferior. 
Origin. 

From the spinous processes of the last two dorsal 
and the three upper lumbar vertebrae. 
Insertion. 

Into the lower borders of the last four ribs beyond 
their angles. 
Nervous supply. 

External posterior branches of the dorsal nerves. 

ACTION OF THE THIRD LAYER. 

The serrati are respiratory muscles acting in antagonism to 
each other. The serratus posticus superior elevates the ribs and 
is, therefore, an inspiratory muscle ; while the serratus posticus in- 
ferior draws the lower ribs downwards, and is a muscle of expira- 
tion. This latter muscle is also probably a tensor of the vertebral 
aponeurosis. 



254 



MYOLOGY. 



FOURTH LAYER. 

(9 muscles.) 
Diagram of 4TH Layer of the Muscles of the BACK. 



Internal set. 



Trachelo-mastoid . 



Transversalis colli -^ 



Spinalis dorsi 
coll 



Longissimus dorsi m> 




External set. 



^Cervicalis ascendens j R ^f * EA ° F 



Accessorius 



Cervical re- 
gion. 



Sacro-lumbalis. 



Dorsal re- 
gion. 



( Lumbar re- 

( GION. 

Erector Spina. 

A rule to remember the external set of this layer may be given 
as follows : 

The first three letters of the first muscle (sacro-lumbalis) S. 
A. C. are the initial letters of the external set in their proper 
order, from below upwards. 



ORIGIN AND INSERTION. 

Trachelo-mastoid (complexus minor). 
Origin. 

From the articular processes of the four lower cervi- 
cal vertebrae, and the four upper dorsal vertebrae. 



MUSCLES OF THE BACK. 2 $$ 

Insertion. 

Into the posterior margin of the mastoid process of 
the temporal bone. 
Nervous supply. 

The external posterior branches of the cervical 
nerves. 
Transversalts Colli. 
Origin. 

From the transverse processes of the first four or 
five upper dorsal vertebrae. 
Insertion. 

Into the posterior tubercles of the transverse pro- 
cesses of the five lower cervical vertebrae. 
Nervous supply. 

The external posterior branches of the cervical 
nerves. 

Cervicalis Ascendens. 
Origin. 

From the angles of the four or five upper ribs. 
Insertion. 

Into the posterior tubercles of the transverse pro- 
cesses of the 4th, 5th and 6th cervical vertebrae. 
Nervous supply. 

The external posterior branches of the cervical 
nerves. 
Musculus Accessorius. 
Origin. 

From the angles of the' six lower ribs. 
Insertion. 

Into the angles of the six upper ribs. 
Nervous supply. 

The external posterior branches of the dorsal nerves. 

Spinalis Colli et Capitis. 
Origin, 

From the spinous processes of the last cervical and 
the two or three upper dorsal vertebra:. 
Insertion. 

(Colli portion). Into the posterior transverse tuber- 
cles of 1st, 2d and 3d cervical vertebra:. 

(Capitis portion). Into the posterior edge of the 
mastoid process and a rough space between the occipi- 
tal curved lines. 



2$6 MYOLOGY. 

Nervous supply. 

The external posterior branches of the cervical 
nerves. 

Spinalis Dorsi. 
Origin. 

From the spinous processes of the two upper lumbar 
and the two lower dorsal vertebrae. 
Insertion. 

Into the spinous processes of from four to eight of 
the middle and upper dorsal vertebrae. 
Nervous supply. 

External posterior branches of the dorsal nerves. 

LONGISSIMUS DORSI. 
Origin. 

From the inner and largest division of the erector 
spinas muscle. 
Insertion. 

A. (Inner set). 1. By separate slips into the trans- 
verse processes of all the dorsal vertebrae. 

2. Into the tubercles (maxillary), on the back of the 
superior articular processes of the lumbar vertebrae. 

B. (Outer set). 1. Into the posterior surfaces of 
transverse processes of lumbar vertebrae. 

2. Into the nine lower ribs internally to their angles. 
Nervous supply. 

External posterior branches of the dorsal nerves. 
Sacro-Lumbalis. 



A division of the erector spinae muscle. 
Insertion. 

By distinct tendons, into the angles of the upper six 
ribs. 
Nervous supply. 

External posterior branches of the lumbar nerves. 
Erector Spik<e. 
Origin. 

i. From the posterior iliac spines. 

2. From the posterior one-fifth of the crest of ilium. 

3. From the spines of the sacrum and posterior 
eminences of sacrum. 

4. From the spinous processes of all the lumbar 
and the three lower dorsal vertebrae. 



MUSCLES OF THE BACK, 



257 



5. By a broad and thick tendon which conceals the 
' muscular fibres. 
Insertion. 

It divides, opposite the last rib, into the sacro-lum- 
balis and longissimus dorsi muscles. 
Nervous supply. 

External posterior branches of both the lumbar and 
the dorsal nerves. 

FIFTH LAYER. 

(8 muscles.) 

Of these muscles the spinales have their point of origin and in- 
sertion in the spinous processes of the vertebrae. The semi-spinales 
arise from the transverse processes of the vertebrae and are in- 
serted into the spinous processes, above the points of origin of the 
various muscles. 

ORIGIN AND INSERTION. 

Semi-spinalis Dorsi. 
Origin. 

From the transverse processes of the 5th. 6th, 7th, 
8th, 9th and 10th dorsal vertebrae. 
Insertion. 

Into the spinous processes of the four upper dorsal 
and the two last cervical vertebrae. 
Nervous supply. 

Internal posterior branches of the dorsal nerves. 
Semi-Spinalis Colli. 
Origin. 

From the transverse processes of the four upper 
dorsal vertebrae. 
Insertion. 

Into the spinous processes of the cervical vertebrae 
from the axis to the 5th. 
Nervous supply. 

Internal posterior branches of the cervical nerves. 

MULTIFIDUS SPIN^E. 

This muscle fills up the groove on either side of the 
spinous processes of the vertebrae from the sacrum to 
the axis. 
Nervous supply. 

Internal posterior branches of both the cervical and 
sacral nerves. 



258 MYOLOGY. 

ROTATORES Spin^e, (eleven pairs). 
Origin. 

From the upper and back part of the transverse pro- 
cesses of the dorsal vertebrae. They are composed of 
the deepest fibres of the multifidus spinae muscle lying 
in the dorsal region. 
Insertion. 

Into the lower margin and posterior surface of the 
laminae and the root of the spinous process of the dor- 
sal vertebra, situated next above their point of origin. 
Nervous supply. 

The internal posterior branches of the dorsal nerves. 

Supra-Spinales. 

Are small fasciculi which lie upon the spinous pro- 
cesses of the vertebrae, in the cervical region. 
Nervous supply. 

Internal posterior branches of the cervical nerves. 

Inter-Spinales. 

Are small muscles placed between the spinous pro- 
cesses of the vertebrae. These are usually arranged 
as six pairs between the lower six cervical vertebrae ; 
four pairs in the lumbar region ; and occasionally two 
pairs attached to the upper and lower dorsal vertebrae. 
Nervous supply. 

Internal posterior branches of the cervical nerves. 

Extensor Coccygis. 
Origin. 

From the posterior surface of the last bone of the 
sacrum. 
Insertion. 

Into the lower part of the coccyx. 
Nervous supply. 

Internal posterior branches of the sacral nerves. 

INTER-TRANSVERSALES, (seven pairs.) 

These muscles are most marked in the cervical 
region, where seven pairs exist ; and are situated be- 
tween the transverse processes of the vertebrae. 
Nervous supply. 

Internal posterior branches of the cervical nerves. 



ACTION OF MUSCLES OF BACK. 



ACTION OF THE MUSCLES OF THE BACK. 



259 



The muscles of the back can be also classified on a basis of 
their action and function as follows : 



The ist Layer. 
The 2nd Layer. 



Those which act on the upper extremity (5) •] 

Those which act upon the ribs and are therefore respiratory ( ^ T 

muscles . . (2) \ ™ E 3 rd La ™> 

Those which move the vertebral column as a whole and are ( ^ T 

extensors (9) } The 4 th Layer. 

Those which move the vertebra upon each other (8) \ The 5TH Layer. 

Total, 24 pairs of muscles. 



The muscles which bend the trunk backwards are , 



Erector spin^e. 
Sacro-lumbalis. 
accessorius. 
longissimus dorsi. 
Spinalis dorsi. 
__ multifidis spin^e. 

The muscles of the back tend to constantly keep the spine 
erect and they act also as an antagonistic force when counterbal- 
ancing heavy weights suspended from the neck, or in cases of great 
abdominal enlargement as occurs in dropsy, pregnancy, or ab- 
dominal tumors. 

The multifidus spince muscle tends also, when acting singly, to 
rotate the trunk towards the side opposite to the muscle in con- 
traction, and it is chiefly by this muscle and the obliquus abdom- 
inis externus, that this motion of the trunk is performed. 

The separate fasciculi of the multifidus spincE and the other 
muscles of the back allow of constant relaxation of some parts 
of the muscles while others are in contraction ; and it is to this 
arrangement that man, in contrast to quadrupeds, is enabled to 
endure an erect spinal posture for so long a time without fatigue. 

The musculus accessorius possesses the power of elevating 
those ribs to which it is attached, provided the cervical vertebra 
becomes a fixed point, and might for that reason be considered 
an auxiliary muscle of i?ispiration. 

NERVOUS SUPPLY OF THE MUSCLES OF THE BACK. 

All the muscles of the back, save one, are supplied with motor 
power from the posterior branches of the spinal nerves. This ex- 
ception is the latissimus dorsi which is supplied by the long sub- 
scapular nerve. 



2CO MYOLOGY. 

m 

D. 

MUSCLES OF THE PERINEUM. 

The muscles of the perineum, in the male, may be thus enum- 
erated. 

Erector Penis. 
Accelerator Urin^e. 
Transversus Perin^ei. 
Compressor Urethra. 
Sphincter Ani. 
Levator Ani. 
Coccygeus. 

In the female, the erector penis becomes the erector clitoridis, 
the accelerator urinse is absent, and the sphincter vaginae is added ; 
so that the same total of muscle is preserved. 

The anterior fibres of the levator ani muscle, in the male, con- 
sist of a distinct band which descends along the sides of the 
prostate gland and encircles it like a sling. This portion was 
pictured by Santorini as a separate muscle, and the name levator 
prostate? muscle has been, by many later anatomists, ascribed to 
it. It seems justly to lay claim to a special name, since it performs, 
in the male sex, a most important part in the act of micturition. 

ORIGIN AND INSERTION. 

Erector Penis. 
Origin. 

1. From the inner surface of the tuberosity of the 
ischium, behind the extremity of the crus-penis. 

2. From the surface of the crus-penis. 

3. From the adjacent portion of ramus of the pubes. 
Insertion. 

Into the sides and the under surface of the crus- 
penis. 
Nervous supply. 

The perineal nerve. 

Accelerator Urin,e. 

This muscle consists of two symmetrical halves united, in the 
median line, by a tendinous raphe. 

Origin. 

1. From the central tendon of the perineum. 

2. From the median raphe. 



. MUSCLES OF THE PERINEUM. 2 6l 

Insertion. 

This muscle invests the bulb of the urethra, and, at 
its anterior part, sends a slip to enclose the corpora 
cavernosa of the penis. 
Nervous supply. 

The perineal nerve. 

TRANSVERSUS PERIN.EI. 

Origin. 

From the inner surface and anterior part of the tu- 
berosity of the ischium. 
Insertion. 

Into the central tendinous point of the perineum, 
joining with its fellow of the opposite side, and with 
the sphincter ani and accelerator urinae muscles. 
Nervous supply. 

The perineal nerve. 
This muscle, in connection with the two muscles named above* 
assists to form a triangular space, which is of surgical importance, 
from the relation of the vessels and nerves contained within it, in 
the operation of lithotomy. 

This triangle is bounded, externally, by the erector penis ; in- 
ternally, by the accelerator urinae ; and, posteriorly, by the trans- 
versa perinad. The contents of this triangular space will be found 
described in detail in the closing pages of this work, descriptive 
of the perineum. 

Compressor Urethra. 
Origin. 

From the upper part of the ramus of the pubes. 
Insertion. 

This muscle, after encircling the membranous por- 
tion of the urethra, unites with its fellow of the oppo- 
site side on the upper and lower surface of that tube. 
Nervous supply. 

The perineal nerve and sometimes by a direct branch 
of the pudic nerve. 

Levator Ani. 
Origin. 

1. Anteriorly, from the posterior surface of the body 
and the ramus of the pubes. 

2. Posteriorly, from the inner surface of the spine of 
the ischium. 



2 62 MYOLOGY. 

3. Between these two points, from the pelvic fascia 
at its angle of division into the obturator and recto- 
vesical fascia. 
Insertion. 

1. Into the sides of the coccyx. 

2. Into the median raphe extending from the coc- 
cyx to the anus. 

3. Into the sides of the rectum. 

4. The anterior fibres encircle the prostate gland 
and join with fibres from the opposite side. 

Nervous supply. 

The perineal nerve and the anterior division of the 
4th sacral nerve. 

Sphincter Ani. 
Origin. 

1. From the tip of the coccyx. 

2. From the superficial fascia, in front of the coccyx. 
Insertion. 

Into the tendinous centre of the perineum. 
Nervous supply. 

The inferior hemorrhoidal branch of the pudic nerve 
and by a branch from the anterior division of the 4th 
sacral nerve. 



COCCYGEUS. 
Origin. 



Insertion. 



1. From the spine of the ischium. 

2. From the lesser sacro-sciatic ligament. 



l i> v 



1. Into the margin of the coccyx. 

2. Into the last bone of the sacrum. 
Nervous supply. 

The anterior division of the 5th sacral nerve. 

ACTION OF THE MUSCLES OF THE PERINEUM. 

The levator prostates muscle, by elevating the prostate gland 
through its sling-like arrangement about it, elevates at the same 
time the contiguous portion of the bladder and with it the uvula 
vesicae. 

By this action, a barrier is placed in contact with the mouth 
of the bladder, effectually assisting in the retention of urine with- 
in its cavity. It is to this muscle, that many authorities ascribe 



A C TION OF M UNCLES OF FERINE UM. 263 

the voluntary control of the bladder and not to the existence of 
elastic fibres or a contractile sphincter at its neck. 

This theory of the action of the muscle seems confirmed by 
certain observed facts during the physiological acts in which the 
levator ani muscle plays so important a part. Thus, in the act 
of defecation, while the feces are entering the cavity of the rec- 
tum and while the levator ani and sphincter ani are fully relaxed, 
the flow of urine becomes almost uncontrollable, from the corre- 
sponding relaxation of the urinary apparatus. On the other hand, 
during the expulsive efforts of the rectal muscles in emptying the 
contents of the rectum, the evacuation of the urine becomes im- 
possible, from the contracted condition of the levator prostatas 
muscle. 

The accelerator urince muscle also performs functions of great 
physiological interest. By its fibres, the bulb of the urethra is 
compressed, and, furthermore, the dorsal vein of the penis is ob- 
structed by an anterior loop of fibres enclosing the body of that 
organ. This muscle is undoubtedly an agent in the ejaculation 
of semen and in the expulsion of the last few drops of urine from 
the urethral canal ; while, by compression of the dorsal vein, it also 
contributes to the persistence of the state of erection of the penis. 

The erector penis, in antagonism to its naturally presupposed 
function, exerts no power over the erection of the genital organ. 
From its attachments, it may slightly compress the sheath and 
contents of the corpus cavernosum but it probably serves with 
its fellow, to maintain a firm and steady positio?i of the organ 
when in a state of erection. 

The transverse perincei muscle, through its insertion into the 
central tendinous point of the perineum, tends to assist the har- 
monious action of the other muscles by affording for them a fixed 
point of resistance. 

The compressor urethra muscle, from its situation and action, 
is sometimes called the " constrictor urethrce" It encloses only 
the membranous portion of the urethral canal, and is principally 
in action during the expulsion of the last drops of urine and the 
ejaculation of semen. It exerts no influence upon erection of 
the penis and none in the ejaculation of the secretions of Cowper's 
glands, whose ducts open anteriorly to it. It is a powerful ad- 
junct in the ejaculation of irritants, when injected into the ure- 
thral canal, in which act it is assisted by the involuntary muscular 
fibres of the urethral walls. 

In the female the sphincter vagina, which is analogous to the 
accelerator urinai muscle in the male, controls the external orifice 



264 



MYOLOGY. 



of the vagina by its contraction. The erector clitoridis performs, 
for that organ, the same function as the erector penis in the male, 
but differs from it in its smaller size, since the clitoris requires less 
muscular support for its proper maintenance, during its erection. 

The levator ani muscle acts as a support to the lower end of 
the rectum and the bladder, during their efforts to expel the feces 
and the urine. In the female, however, it gives additional sup- 
port to the vaginal walls. 

The coccygeus muscle supports and raises the coccyx, after it 
has been displaced backward during the acts of defecation or of 
parturition. 

NERVOUS SUPPLY OF THE MUSCLES OF THE 
PERINEUM. 

The nervous supply to all the muscles of the perineum, save 
one, is derived from one source, namely, the branches of the inter- 
nal pudic nerve. The special branches of this nerve, however, 
which supply the muscles of the perineum are as follows : 

(Inferior hemorrhoidal branch of in- / Erector penis - 

ternal pudic nerve p \^ //Accelerator urin^e. 

Transversus perinei. 

Perineal nerve (cutaneous branch). . . 2 >^V //>C / Compressor urethra. 

Sphincter ani externus. 

Levator ani. 
Perineal nerve (muscular branches). . fi^ \ / Coccygeus. 

Erector clitoridis. 

'Sphincter vagina. 

5th Sacral nerve (ant. branch) ^ ^Sphincter ani internus. 

Total, 11 muscles. 

Deduct one muscle supplied from 
two sources (the spincter ani). 

Total, 10 muscles. 

CAVITIES OF THE TRUNK. 

Appended to the trunk, whose muscles we have been consid- 
ering in this chapter, are two large cavities, viz., the cavity of the 
thorax and the cavity of the abdomen. 

These cavities contain important viscera and large arterial, 
venous, and nervous trunks. Important ganglia are also located 
within these special regions, and the sympathetic system is here 
most extensively developed. 




CAVITIES OF THE TRUNK. 2 6$ 

In the following- pages, will be found the boundaries of these 
two cavities arranged in a tabular form, and also an enumeration 
of the openings which normally exist in the abdominal walls and 
the exact anatomical situation of each. Some of these openings 
have already been described in connection with the external ob- 
lique muscle, while others, pertaining to the diaphragm and to 
the pelvic region, have not been previously mentioned. 

I. 
ABDOMINAL CAVITY. 

The cavity of the abdomen is oval in shape and is bounded as 

follows : 

Above by the \ Diaphragm. 

Below bv the \ Levator ani - i Forming the floor of the 

y * I Coccygeus. / pelvis. 

["Rectus abdominis. 

rr, , . 77 • , c PYRAMIDALIS. 

I he anterior wall consists of < T 

LlNEA ALBA. 
[LlNEA SEMILUNARIS. 
C Obliquus ABDOMINIS EXTERNUS. 

The lateral wall consists of ■< Obliquus abdominis internus. 

( Transversalis abdominis. 

Lumbar vertebra. 

Crura of Diaphragm. 

, QUADRATUS LUMBORUM. 

The posterior wall consists of \ ^ SQAS pARVUS> 

I Psoas magnus. 
!^Iliacus. 

II. 
THORACIC CAVITY. 

The thoracic cavity is bounded as follows : 

ist Dorsal vertebra. 

Above (thoracic entrance) \ ist Rib. 

Upper edge of sternum. 
Sternum. 

In front by the \ Costal cartilages. 

Inner surface of the upper ribs, 
nner surface of the ribs. 
Intercostal muscles, 
I Dorsal vertebra. 

Posteriorly by the ■< Inner surface of the ribs. 

( Intercostal muscles. 
Below by the \ Diaphragm. 

Openings in the Abdominal Walls. 

There are 10 openings in the abdominal walls in the male sex, 
and 1 1 openings in the female sex. 

These openings may be classified as follows : 



Laterally by the •] y 



266 



MYOLOGY. 



Upwards, through the j 



diaphragm. 



Forwards, 



Downwards. 



(3) 



(Esophageal*-* muscular open- i CEs0pHAGUS> 

ing, on eve] of ? th dorsal ver- \ p NEUMOGASTRIC ^ RVEt 

tebra — transmitting ) 

Aortic " — a tendinous opening, ) Aorta. 
on level with 12th dorsal verte- >-VENA AZYGOS. 

bra — transmitting ) THORACIC DUCT. 

Cava opening," called " foramen^ 
quadratum," — tendinous, oppo- 
site the 9th dorsal vertebra, — 
transmitting 



Vena cava ascendens. 



{Umbilicus, 
Internal abdominal rings, (one on each side.) 
Femoral rings, (one on each side.) 

( For urethra, 
(2 or 3) ■< " rectum 

( " vagina (in female.) 



MUSCLES OF THE UPPER EXTREMITY. 

There are 62 pairs of muscles connected with the skeleton of 
the upper extremity, They may be thus divided : 

I. Extrinsic Muscles, 12 

II. Intrinsic " 50 

Total 62 muscles. 

By an extrinsic muscle is meant a muscle which serves to con- 
nect the upper extremity to some other part of the skeleton. 

By an intrinsic muscle, is meant one which serves to connect 
the various segments of the extremity with each other. 



I. 



EXTRINSIC MUSCLES OF THE UPPER EXTREMITY. 

The twelve pairs of muscles connected with the two upper 
extremities, may be divided into three distinct sets. 

(1) Those connecting the upper extremity to the head. 

(2) Those connecting the upper extremity to the back of the 
trunk. 

(3) Those connecting the upper extremity to the anterior and 
lateral walls of the trunk. 

The various muscles included under each of these groups will 
be shown in the following table. 



MUSCLES OF UPPER EXTREMITY. 



267 



Extrinsic muscles 
of the upper ex-^ 
tremity : 



( Sterno-mastoid. 
f Connecting the upper extremity to 3 Sterno _ hyoid< 
the head and the neck . . (3) ] Qmo-HYOID. 

Trapezius. 
Latissimus dorsi. 



Connecting the upper extremity to { Rhomboideus MINO r. 

tne 0ack ^ Rhomboideus major. 

[Levator anguli scapula. 

l r ,. ,, , ., , fPECTORALIS MINOR. 

Connecting the upper extremity tc , I Pectoralis major> 
.the *»&»*> and fe&ro/ A^of S ubclavius. 

I the trUnk ^) [ Serratus MAGNUS. 

Total, 12 



ORIGIN AND INSERTION. 



Trapezius. 
Origin. 

1. From the external occipital protuberance. 

2. From the inner third of the superior curved line 
of the occipital bone. 

3. From the ligamentum nuchae. 

4. From the spinous processes of the last cervical, 
and of all the dorsal vertebrae. 

5. From the supra-spinous ligament of the vertebral 
column. 

Insertion. 

1. Into the posterior border of the outer third of 
the clavicle. 

2. Into the inner border of the acromion process of 
the scapula. 

3. Into the whole length of the upper lip of the 
posterior border of the spine of the scapula. 

4. Into a tubercle, near the inner extremity of the 
spine. 

Nervous supply. 

From two sources, viz., the spinal accessory or nth 
cranial nerve, and the deep branches of the cervical 
plexus. 

Latissimus Dorsi. 
Origin. 

1. From the spinous processes of the 6 or 7 lower 
dorsal vertebrae. 

2. From the posterior layer of the lumbar apo- 
neurosis. 

3. From the lumbar and sacral spines. 



268 MYOLOGY. 

4. From the posterior part of the outer lip of the 
crest of the ilium. 

5. From the last three or four ribs, interdigitating 
with the fibres of the external oblique muscle. 

6. Occasionally from the inferior angle of the scap- 
ula. 

Insertion. 

Into the bottom of the bicipital groove of the hu- 
merus. 
Nervous supply. 

From the long subscapular nerve, derived from the 
brachial plexus. 

Rhomboideus Minor. 
Origin. 

1. From the ligamentum nuchae of the vertebrae. 

2. From the spinous process of the 7th cervical 
vertebra. 

Insertion. 

Into the posterior border of the scapula, near the 
root of the spinous process of that bone. 
Nervous supply. 

From the fifth cervical nerve, before it assists to 
form the brachial plexus. 

Rhomboideus Major. 
Origin, 

1. From the spinous processes of the 4 or 5 upper 
dorsal vertebrae. 

2. From the supra-spinous ligament of the vertebrae. 
Insertion. 

Into a tendinous arch, connected with the posterior 
border of the scapula. 
Nervous supply. 

From the fifth cervical nerve, before it assists to 
form the brachial plexus. 

Levator Anguli Scapula. 
Origin. 

From the posterior tubercles of the transverse pro- 
cesses of the upper three, four, or five cervical ver- 
tebrae. 
Insertion. 

Into the posterior border of the scapula between 



MUSCLES OF UPPER EXTREMITY. 



269 



the root of the spine and the superior angle of that 
bone. 
Nervous supply. 

From the fifth cervical nerve, and from the deep 
branches of the cervical plexus. 

Pectoralis Major. 
Origin. 

1. From the anterior surface of the inner half of the 
clavicle. 

2. From the corresponding half of the front of the 
sternum. 

3. From the cartilages of the true ribs, excepting 
occasionally the 1st and 7th. 

4. From the aponeurosis of the external oblique 
muscle of the abdomen. 

Insertion. 

Into the anterior lip of the bicipital groove of the 
humerus. 
Nervous supply. 

From the anterior thoracic branches of the brachial 
plexus of nerves. 

Pectoralis Minor. 
Origin. 

From the outer surface and the upper border of the 
3rd, 4th and 5th ribs, near to their cartilages, and from 
the aponeurosis covering the intercostal muscles. 
Insertion. 

Into the inner border of the coracoid process of the 
scapula. 
Nervous supply. 

From the anterior thoracic branches of the brachial 
plexus. 

SUBCLAVIUS. 
Origin. 

From the cartilage of the first rib, in front of the 
rhomboid ligament of the clavicle. 
Insertion. 

Into a groove on the under surface of the middle 
third of the clavicle. 
Nervous supply. 

A supra-clavicular branch of the brachial plexus. 



270 MYOLOGY. 

Serratus Magnus. 
Origin. 

By nine fleshy digitations, from the outer surface 
and the upper border of the eight upper ribs. (The 
2nd rib having two digitations). 
Insertion. 

Into the whole length of the anterior lip of the pos- 
terior border of the scapula. 
Nervous supply. 

From the posterior or long thoracic nerve. 

ACTION OF THE EXTRINSIC MUSCLES OF THE 
UPPER EXTREMITY. 

The action of these muscles is demanded in various move- 
ments of the head, scapula and the humerus, If the head be 
made a fixed point, the trapezius muscle helps, through its upper 
fibres, to elevate the point of the shoulder, as in the acts of sup- 
porting weights, shrugging the shoulders, etc.; while, by means of 
its middle and lower fibres, a partial rotation of the scapula upon 
the side of the chest is produced. When the shoulders are fixed, 
both of the trapezii muscles, if acting together, will draw the 
head directly backwards ; or, if only one act, the head will be 
drawn towards the corresponding side. 

The latissimus dorsi muscle, if the trunk be the fixed point, acts 
upon the arm and draws it downwards and backwards and subse- 
quently rotates the arm inwards, as is illustrated in the act of 
scratching the gluteal region. If this muscle acts in connection 
with the pectoralis major and the teres major muscles, the arm is 
adducted and closely approximated to the chest wall. If the arm 
be made a fixed point, the latissimus dorsi may assist in forcible 
inspiration by elevating the lower ribs (as is illustrated in the 
attitude assumed by asthmatic patients) ; or if it act in connec- 
tion with the pectoral and abdominal muscles, while the arms 
are made a point of resistance, the whole trunk may be drawn 
forward or upward, as is illustrated in the acts of climbing or 
walking upon crutches. 

The levator anguli scapidce raises the angle of the scapula, after 
it has been depressed by the trapezius ; and, if the shoulder be a 
fixed point, it may tend to incline the neck to the corresponding 
side. 

The rhomboid muscles, by carrying the angle of the scapula 
backwards and upwards, often produce a slight rotation of the 



MUSCLES OF UPPER EXTREMITY. 



271 



scapula upon the sides of the chest. If the shoulder be made a 
fixed point, these muscles will draw the scapula directly back- 
wards towards the spinal column ; and, in this act, they are 
assisted by the middle and the inferior fibres of the trapezius. 

The pec t oralis major muscle acts most frequently, in conjunc- 
tion with the teres major and the latissimus dorsi, in approxima- 
ting the arm to the chest wall after the arm has been raised by 
the action of the deltoid. If it act singly, this muscle tends to 
draw the arm forwards and inwards, thus bringing it across the 
anterior wall of the chest. If the arm be made a fixed point, this 
muscle, in connection with the pectoralis minor, the subclavius, 
and the latissimus dorsi, acts upon the ribs and thus all four of 
these muscles become aids to forcible inspiration. 

The pectoralis 'minor muscle tends to depress the point of the 
shoulder and to draw the scapula downwards and inwards towards 
the thorax. 

The subclavius muscle also depresses the shoulder, by drawing 
the clavicle downwards and forwards. 

The serratus magnus muscle is a most important inspiratory 
muscle. When the shoulders are fixed, it elevates the ribs and 
expands the chest wall and thus increases the size of the chest 
cavity. It also tends to elevate the point of the shoulder, by 
causing a rotation of the scapula, since it draws forwards the in- 
ferior angle and the base of the shoulder blade. It greatly assists 
the trapezius in supporting weights upon the shoulder, the thorax 
being at the same time rendered a fixed point, by preventing the 
escape of the included air. 



272 



MYOLOGY. 



II. 

INTRINSIC MUSCLES OF THE UPPER EXTREMITY. 

The fifty intrinsic muscles of the upper extremity may be 
divided into four groups, viz. : 

(A) Those connecting the arm to the shoulder, 7 muscles. 

(B) " situated upon the arm, 4 " 

(C) The muscles of the fore-arm, 20 " 

(D) " " " " hand, 19 " 

Total, ... 50 

A. 

MUSCLES OF THE SCAPULO-HUMERAL REGION. 

A. The muscles of the SCAPULO-HUMERAL REGION, or those 
which connect the skeleton of the shoulder with that of the arm, 
include the following seven muscles : 





1. Deltoid. 




2. Supra-spinatus. 




3. Infra-spinatus. 




4. Teres minor. 




5. Teres major. 




6. Subcapularis. 




7. Coraco-brachialis, 




ORIGIN AND INSER 


Deltoid. 




Origin. 





1. From the upper surface and the anterior border 
of the outer half of the clavicle. 

2. From the outer border of the acromion process 
of the scapula. 

3. From the whole length of the lower lip of the 
posterior border of the spine of the scapula. 

Insertion. 

Into a rough, triangular prominence, a little above 
the middle of the outer surface of the humerus. 
Nervous supply. 

The circumflex nerve. 



MUSCLES OF SCAPULO-HUMERAL REGION. 



273 



Supra-Spinatus. 
Origin. 

1. From the inner two-thirds of the supra-spinous 
fossa of the scapula. 

2. From the fascia which covers it. 
Insertion. 

Into the highest- of the three facets upon the greater 
tuberosity of the humerus. 
Nervous supply. 

The supra-scapular nerve. 

Infra-Spinatus. 
Origin. 

1. From the inner two-thirds of the infra-spinous 
fossa of the scapula. 

2. From the fascia, which separates it from the teres 
major and minor muscles. 

Insertion. 

Into the middle facet upon the greater tuberosity 
of the humerus. 
Nervous supply. 

The supra-scapular nerve. 

Teres Minor. 
Origin. 

1. From the upper two-thirds of the dorsal aspect 
of the axillary border of the scapula. 

2. From the inter-muscular septa, which separate it 
from the teres major and infra-spinatus muscles. 

' Insertion. 

I. Into the lowest facet upon the greatest tuber- 
osity of the humerus. 

2. By a few fibres, occasionally, into the neck of 
the humerus. 
Nervous supply. 

A branch of the circumflex nerve. 

Teres Major. 

Origin. 

1. From the dorsal aspect of the inferior angle of 
the scapula. 

2. From the inter-muscular septa, which separate it 
from the teres minor and the infra-spinatus muscles. 



274 MYOLOGY. 

Insertion . 

Into the posterior lip of the bicipital groove of the 
humerus. 
Nervous supply. 

The lower subscapular nerve. 

Subscapulars. 
Origin. 

1. From the inner two-thirds of the subscapular 
fossa. 

2. From the aponeurosis, which separates it from 
teres major muscle. 

Insertion. 

Into the lesser tuberosity of the humerus, and, occa- 
sionally, by a few fibres into the neck of that bone. 
Nervous supply. 

The two upper subscapular nerves. 

Coraco-Brachialis. 
Origin. 

From the tip of the coracoid process of the scapula, 
in common with the short head of the biceps. 
Insertion. 

Into a rough ridge situated a little above the 
middle of the inner surface of the shaft of the hu- 
merus. 
Nervous supply. 

The musculo-cutaneous nerve. 

ACTION OF THE MUSCLES FORMING THE SCAP- 
ULOHUMERAL GROUP. 

The direct action of these seven muscles may be thus classified : 

( Pectoralis maior (assisting). 

Muscles producing adduction of the arm •< Latissimus dorsi (assisting). 

( Teres major. 

Muscles producing abduction of the arm j gupra-spinatus. 

( Teres major. 

Muscles producing internal rotation of the arm •< Subscapularis. 

( Latissimus dorsi. 

Muscles producing external rotation of the arm \ T ". 

r & (1 eres minor. 

Muscles producing flexion of the arm \ Coraco-brachialis. 

The deltoid muscle raises the arm away from the side, so as to 
bring it at a right angle to the trunk. Its anterior fibres assist the 
pectoralis major in drawing the arm forwards ; while its posterior 



MUSCLES OF SCAPULOHUMERAL REGLON. 



275 



fibres assist the latissimus dorsi and the teres major in drawing 
the arm backwards. 

The supra-spinatus muscle assists the deltoid in raising the 
arm from the side, and tends to fix the head of the humerus firmly 
in its socket. 

The infra-spinatus and teres minor muscles tend to rotate the 
arm outward, when the arm hangs at the side ; but, when the arm 
is raised, they help to sustain it. in that position or to carry it 
backwards. 

The supra-spinatus, infra-spinatus, teres minor and subscapularis 
muscles, in consequence of their close connection with the capsular 
ligament, may be styled " capsular muscles " ; and when they all 
act together, they press the head of the humerus against the glen- 
oid cavity and thus prevent dislocation. 

The teres major muscle assists the latissimus dorsi in drawing 
the arm downwards and backwards, when previously raised, and 
also to rotate the arm inwards, when it hangs parallel to the chest 
wall. It assists also in drawing the trunk forwards, when the arm 
is made a fixed point, in which act it is greatly aided by the pec- 
toralis major and minor and the latissimus dorsi. An illustration 
of this function is seen in the act of climbing, or of walking upon 
crutches. 

The coraco-brachialis muscle assists in the acts of flexion a,nd 
of elevation of the arm. 

NERVOUS SUPPLY OF MUSCLES FORMING THE 
SCAPULO-HUMERAL GROUP. 

The nerve supply of this group of muscles is as follows : 

rr,, • n ,. , x ( Deltoid. 

I he circumflex nerve supplies (2) \ ^ 

J vr v ' { 1 eres minor. 

The suprascapular nerve supplies (2) -i Supra-spinatus. 

r r rr I Infra- spinatus. 

The sub-scapular nerve supplies (2) \ Subscapularis. 

r FF w I Teres major. 

The musculo- cutaneous nerve supplies (1) ■{ Coraco-brachialis. 

7 

POINTS OF SURGICAL INTEREST PERTAINING TO 
THE SCAPULO-HUMERAL GROUP OF MUSCLES. 

There are two important spaces formed in this region, into the 
composition of which the teres major and teres minor muscles of 
this group enter, and through which the circumflex and dorsalis 
scapulce vessels pass. These spaces are formed as follows : 



2/6 MYOLOGY, 




tgm Teres miner. 



Teres major. 



(A.) A quadrilateral space bounded by the surgical neck of 
the humerus, the teres minor, the subscapular head of 
the triceps, and the teres major. It gives passage to 
the posterior circumflex artery and vein and to the cir- 
cumflex nerve. 
(B.) A triangular space bounded by the triceps, teres minor, 
and teres major muscles. It gives passage to the dor- 
salis scapula artery and vein. 
The subscapularis is a powerful defence to the front of the 
shoulder joint, and tends to prevent displacement of the hu- 
merus forwards. The teres minor and infraspinatus muscles pro- 
tect the joint posteriorly ; and the supra spinatus muscle and the 
projection of the acromion process of the scapula, shield the 
upper portion of the articulation. 

In the various forms of fracture of the humerus, which are met 
with above the junction of the middle and upper third of that 
bone, these muscles produce special forms of displacement of the 
fragments, wmich are of great value in determining the seat of 
fracture. 

Thus in case of the separation of the greater tubercle of the 
humerus, the fragment is drawn by the infraspinatus and teres 
minor muscles into close contact with the dorsum of the scapula ; 
while the humerus is rotated inwards by the subscapularis, teres 
major and latissimus dorsi muscles (since the antagonistic force of 
the external rotator muscles is removed) and the arm is approxi- 
mated to the chest and drawn forwards by the pectoralis major. 

In case of fracture of the surgical neck of the humerus, the 
upper fragment is slightly elevated by the muscles attached to 
the greater and lesser tuberosities ; and the lower fragment is 
drawn inwards by the pectoralis major, the latissimus dorsi, and 
teres major muscles. In some cases, the deltoid muscle produces 
also a displacement of the lower fragment obliquely outwards from 
the chest and occasionally elevates it to a marked degree. 

In case of fracture of the shaft of the humerus below the point 
of insertion of the teres major muscle, the upper fragment will be 



MUSCLES OF THE ARM. 



277 



drawn forcibly inwards by the teres major, latissimus dorsi and 
pectoralis major muscles ; and the lower fragment will be drawn 
upwards by the deltoid. 

If the shaft of the humerus be fractured below the point of in- 
sertion of the deltoid, the amount of the deformity will be influ- 
enced greatly by the direction of the fracture. 

If the direction of the fracture be transverse, only a slight de- 
formity will ensue, since the bone still acts as a counter-extend- 
ing force to the muscles ; but, if the direction of the fracture be 
oblique, the biceps, brachialis anticus, and the triceps muscles will 
cause a marked displacement of the lower fragment upwards, since 
the ends of the injured bone can be easily made to slide upon 
each other and therefore no obstacle to muscular contraction will 
exist. 

B. 

MUSCLES SITUATED UPON THE ARM. 

The four muscles situated upon the arm may be divided into 
two groups : 

(1) Those attached to the anterior surface of the hu- j Biceps flexor cubiti. 

merus (2) \ Brachialis anticus. 

(2) Those attached to the posterior surface of the hu- j Triceps extensor cubiti 

merus (2) \ Subanconeus. 

ORIGIN AND INSERTION. 

Biceps Flexor Cubiti. 
Origin. 

Short head. From the tip of the coracoid process 
of the scapula in common with the coraco-brachialis 
muscle. 

Long head. I. From the top of the glenoid cavity 
of the scapula. 

2. From the glenoid ligament of the shoulder joint. 
Insertion. 

Into the posterior aspect of the bicipital tuberosity 
of the radius. 
Nervous supply. 

The musculocutaneous nerve. 

Brachialis Anticus. 
Origin. 

I. From the lower half of both the inner and outer 
surfaces of the shaft of the humerus. 



278 MYOLOGY. 

2. From an internal and an external inter-muscular 
septum. 
Insertion. 

Into a rough triangular, surface on the front part of 
the coronoid process of the ulna. 
Nervous supply. 

The musculo-cutaneous nerve and a filament from 
the musculo-spiral nerve. 

Triceps Extensor Cubiti. 
Origin. 

Long heacF. 

1. From a depression bek>w the glenoid cavity, and 
from the adjoining portion of the outer border of the 
scapula. 

2. From the capsular ligament of the shoulder joint. 
Outer head. 

1. From the posterior surface of the shaft of the 
humerus, above the musculo-spiral groove. 

2. From the outer border of the humerus. 

3. From the external inter-muscular septum. 
Inner head. 

1. From the posterior surface of the shaft of the 
humerus, below the musculo-spiral groove. 

2. From the inner border of the humerus. 

3. From the internal inter-muscular septum. 
Insertion. 

By a strong tendon, into the posterior and upper 
part of the olecranon process of the ulna. 
Nervous supply. 

The musculo-spiral nerve. 

Sub- anconeus. 
Origin. 

From the posterior surface of the humerus, above 
the olecranon fossa. 
Insertion. 

Into the posterior ligament of the elbow joint. 
Nervous supply. 

The musculo-spiral nerve. 



MUSCLES OF THE ARM. ■ 279 

ACTION OF THE MUSCLES OF THE ARM. 

The biceps first supinates the hand and then flexes the fore- 
arm ; it also renders tense the fascia of the forearm by its aponeu- 
rotic tendinous expansion. 

The bracJiialis anticus muscle, from its anatomical situation, 
forms a most important defence to the elbow joint which it covers. 

The brachialis anticus muscle also flexes the forearm, and, in 
cases where the forearm becomes a fixed point, this muscle and 
the biceps tend to flex the arm upon the forearm, as illustrated in 
the act of climbing. 

The triceps extensor cubiti is the antagonist of the biceps and 
brachialis anticus muscles, and is an extensor of the forearm 
upon the arm. It becomes therefore a powerful agent in the 
act of striking a blow with the hand, acting in connection with 
the pectoralis major and the coraco-brachialis. 

The triceps extensor cubiti, from its relation to the shoulder 
joint, forms a formidable barrier to displacement of the head of 
the humerus downwards or backwards. When the arm and the 
forearm are extended, the triceps muscle may assist the teres major 
and the latissimus dorsi muscles in drawing the humerus back- 
wards. 

NERVOUS SUPPLY OF THE MUSCLES OF THE ARM. 

The anterior group is supplied by the musculo-cutaneo74s nerve. 
The posterior group is supplied by the musculo -spiral nerve. 

POINTS OF SURGICAL INTEREST PERTAINING TO 
THE MUSCLES OF THE ARM. 

In those forms of fractures of the humerus, occurring imme- 
diately above the condyles, the muscles of the arm are agents in 
producing the deformity. If the fracture be oblique, from above 
downwards and forwards, the lower fragment is drawn upwards 
and backwards by the combined force of the biceps, brachialis 
anticus and the triceps muscles ; but if the obliquity be in the 
opposite direction, the displacement of the lower fragment is for- 
wards and upwards. 

In fracture of the olecranon process of the ulna, the triceps 
muscle produces a displacement of the fragment upwards tor a 
distance varying from one-half an inch to two inches (provided the 



280 MYOLOGY. 

tendinous aponeurosis of that muscle is completely detached from 
the remaining portion of the ulna), and the power of extension of 
tliz forearm upon the arm is lost. 

In fracture of the coronoid process of the ulna, the brachialis 
anticus muscle elevates the fragment and the power of flexion 
of the elbow joint is partially destroyed. 

In fracture of the neck of the radius, the lower fragment is 
drawn upwards by the biceps muscle ; and the action of the supin- 
ator brevis and the pronator radii teres muscles tend also to 
disturb the relation of the two fragments to each other. 

The inner border of the coraco-brachialis and biceps muscles 
serves as a guide to the brachial artery, in its course down the 
inner aspect of the arm. 



MUSCLES OF THE FOREARM. 2 8l 

c. 

MUSCLES OF THE FOREARM. 

The muscles of the forearm are 20 in number, and may be 
divided into two sets. 

1. Those on the anterior surface, 8 

2. " " " posterior " 12 

20 
On both surfaces, the muscles are arranged in two layers, viz., 
a superficial and deep layer. d 



MUSCLES OF ANTERIOR SURFACE OF FOREARM, 



o c - f Pronator radii teres. 

J Flexor carpi radialis 
Superficial layer, (5)-) Palmaris longus. 

I Flexor sublimis digitorum. 
[_ Flexor carpi ulnaris. 



o4 






( Flexor longus pollicis. 
(_ Deep layer, (3) •< Flexor profundis digitorum. 

g w _ ( Pronator quadratus. 

Total 8 
The muscles of the superficial layer all arise from the internal 
condyle of the humerus, either entirely or in part. 

ORIGIN AND INSERTION OF THE ANTERIOR 

GROUP. 

SUPERFICIAL LAYER. 
(5 muscles). 

Pronator Radii Teres. 

\in. 

Large or superficial head. 

1. From the inner condyle and the inner border of 
the humerus. 

2. From the deep fascia of the forearm. 

3. From the inter-muscular septum, between it and 
the flexor carpi radialis, 

Small or deep head. 

I. From the inner surface of the coronoid process 
of the ulna. 



2S2 MYOLOGY. 

Insertion. 

Into the rough depression, situated at about the 
middle of the outer surface of the shaft of the radius. 
Nervous supply. 

The median nerve. 

Flexor Carpi Radialis. 
Origin. 

1. By the common tendon arising from the inner 
condyle of the humerus. 

2. From the deep fascia of the forearm. 

3. From the inter-muscular septa. 
Insertion. 

Into the palmar surface of the base of the meta- 
carpal bone of the index-finger. 
Nervous Supply. 

The median nerve. 

Palmaris Longus. 
Origin. 

1. By the common tendon, from the inner condyle 
of the humerus. 

2. From the deep fascia of the right forearm. 

3. From the inter-muscular septa. 
Insertion. 

1. Into the anterior annular ligament of the carpus, 

2. Into the palmar fascia. 
Nervous Supply. 

The median nerve. 

Flexor Sublimis Digitorum. 
Origin. 

Inner head. 

1. From the inner condyle of the humerus, by 
means of the common tendon. 

2. From the internal lateral ligament of the elbow 
joint. 

Middle head. 

From a tubercle on the inner side of the coronoid 
process of the ulna. 

Outer head. 

From an oblique line on the front of the radius. 
Insertion. 

Into the sides of the 2d phalanges of each of the four 
finders. 



MUSCLES OF THE FOREARM. 



283 



Nervous Supply. 

The median nerve. 

Flexor Carpi Ulnaris. 
Origin. 

Anterior or inner head. 

1. From the internal condyle, by means of the com- 
mon tendon. 

2. From the deep fascia of the forearm. 

3. From the inter-muscular septum. 
Posterior or outer head. 

1. From the inner border of the olecranon process. 

2. From the upper two-thirds of the posterior por- 
tion of the shaft of the ulna. 

Insertion. 

1. Into the pisiform bone and slightly into the 5th 
metacarpal bone. 

2. Into the annular ligament. 
Nervous supply. 

The ulnar nerve. 

DEEP LAYER. 
(3 muscles.) 

Flexor Longus Pollicis. 



1. From the upper two-thirds of the anterior sur- 
face of the shaft of the radius. 

2. From the interosseous membrane. 

3. Occasionally by a slip from the coronoid process 
of the ulna. 

Insertion. 

Into the base of the last phalanx of the thumb. 
Nervous supply. 

The median nerve. 
Flexor Profundis Digitorum. 
Origin. 

1. From the inner side of the coronoid process of 
the ulna. 

2. From the upper two-thirds of the anterior and 
the inner surfaces of the ulna. 

3. By an aponeurosis, common to it and the flexor 
carpi ulnaris, from the upper two-thirds of the pos- 
terior surface of the ulna. 



284 



MYOLOGY. 



4. From the inner half of the interosseous mem- 
brane. 
Insertion. 

Into the bases of the 3d phalanges of each of the 
four inner fingers. 
Nervous supply. 

The median and ulnar nerves. 
Pronator Quadratus. 
Origin. 

1. From the inner fourth of the anterior surface 
and the inner border of the ulna. 

2. From an aponeurosis covering the inner portion 
of the muscle. 

Insertion. 

Into the lower fourth of the anterior surface and 
the outer border of the radius. 
Nervous supply. 

The median nerve. 

ACTION OF THE MUSCLES OF ANTERIOR SUR- 
FACE OF THE FOREARM. 



' Pronator radii teres. 

Flexor carpi radialis 

£ f Superficial layer, (s)«j p a lmaris longus 

B 



o 



o o 



g [_ Deep layer, 



(3) 



Flexor sublimis digitorum. 
.Flexor carpi ulnaris 

Flexor longus pollicis 

Flexor profundus digitorum 
^Pronator quadratus 




Action. 

2 Pronators. 



3 Flexors of 
hand. 



Flexors of 



fingers. 



NERVOUS SUPPLY OF THE MUSCLES OF THE AN- 
TERIOR SURFACE OF THE FOREARM. 



The median nerve supplies. 



r Pronator radii teres. 

Pronator quadratus. 

Flexor carpi radialis. 
)^- muscles. -{ Flexor sublimis digitorum. 
I Flexor longus pollicis. 
I \ of Flexor profundus digitorum. 
[ Palmaris longus. 



The ulnar nerve supplies. 



ii- muscles 



j Flexor carpi ulnaris. 



I- of Flexor profundus digitorum. 



MUSCLES OF THE FOREARM. 



285 



MUSCLES OF POSTERIOR SURFACE OF FOREARM. 

The muscles situated npon the posterior surface of the fore- 
arm may be thus classified : 



O A 
<L) O 



+-« .Co <D 



-.2 

3 j-i 



Superficial layer, (7) -{ 



r Supinator longus. 
Extensor carpi rad. longior. 
Extensor carpi rad. brevior. 
Extensor communis digitorum, 
Extensor minimi digiti. 
Extensor carpi ulnaris. 
x^nconeus. 



f Supinator brevis. 
I Extensor ossis metacarpi pollicis. 
Deep layer, (5)^ Extensor primi internodii pollicis. 

^ Extensor secundi internodii polli. 

^ Extensor indicis 
The superficial group arise entirely or in part from the exter- 
nal condyle or the external ridge of the humerus. 

ORIGIN AND INSERTION OF THE POSTERIOR 

GROUP. 

SUPERFICIAL LAYER. 
(7 muscles.) 

Supinator Longus. 
Origin. 

1. From the upper two-thirds of the external con- 
dyloid ridge of the humerus. 

2. From the inter-muscular septum on its outer side. 
Insertion. 

Into the outer side of the base of the styloid process 
of the radius. 
Nervous supply. 

The musculo-spiral nerve. 

Extensor Carpi Radialis Longior. 
Origin. 

1. From the lower third of the external condyloid 
ridge of the humerus. 

2. From the inter-muscular septum. 
Insertion. 

Into the base of the 2nd metacarpal bone. 
Nervous Supply. 

The musculo-spiral nerve. 



286 MYOLOGY. 

Extensor Carpi Radialis Brevior. 
Origin. 

1. By a common tendon, from the external condyle 
of the humerus. 

2. From the external lateral ligament of the elbow 
joint. 

3. From the deep fascia of the forearm. 

4. From the inter-muscular septa. 
Insertion. 

Into the posterior part of the base of the third met- 
acarpal bone. 
Nervous Supply. 

The posterior interosseous nerve. 

Extensor Communis Digitorum. 
Origin. 

1. By the common tendon, from the -external con- 
dyle of the humerus. 

2. From the deep fascia of the forearm. 

3. From the inter-muscular septa. 
Insertion. 

Into the bases of the 2nd and 3rd phalanges of the 
four fingers. 
Nervous Supply. 

.The posterior interosseous nerve. 

Extensor Minimi Digiti. 
Origin. 

1. From the external condyle of the humerus, by a 
common tendon. 

2. From the deep fascia of the forearm. 

3. From the inter-muscular septa. 
Insertion. 

In common with the tendon of the extensor com- 
munis digitorum, with which it is joined to the 2nd 
and 3rd phalanges of the little finger. 
Nervous supply. 

The posterior interosseous nerve. 

Extensor Carpi Ulnaris. 
Origin. 

1. By the common tendon, from the external con- 
dyle of the humerus. 

2. From the middle third of the posterior border 
of the shaft of the ulna. 



MUSCLES OF THE FOREARM. 



287 



3. From the deep fascia of the forearm. 

4. From the inter-muscular septum, between it and 
the extensor minimi digiti. 

Insertion. 

Into the base of the metacarpal bone of the little 
finger. 
Nervous supply. 

The posterior interosseous nerve. 

Anconeus. 
Origin. 

T. From the back of the outer condyle of the 
humerus. 

2. From the deep fascia of the forearm. 
Insertion. 

1. Into the outer side of the olecranon process of 
the ulna. 

2. Into the upper third of the posterior surface of 
the shaft of the ulna. 

Nervous supply. 

The musculo-spiral nerve. 

DEEP LAYER. 

(5 muscles.) 

Supinator Brevis. 
Origin. 

1. From the external condyle of the humerus. 

2. From the external lateral ligament of the elbow- 
joint. 

3. From the orbicular ligament of the radius. 

4. From a depression and a ridge below the lesser 
sigmoid cavity of the ulna. 

Insertion. 

1. Into the inner, the anterior and the outer surface 
of the radius above its tuberosity. 

2. Into the oblique line upon the radius as low 
down as the insertion of the pronator radii teres. 

Nervous Supply. 

The posterior interosseous nerve. 

Extensor Ossis Metacarpi Pollicis. 
Origin. 

1. From the outer half of the posterior surface of 
the shaft of the ulna. 



2 88 MYOLOGY. 

2. From the posterior surface of the interosseous 
membrane. 

3. From the middle third, of the posterior surface 
of the shaft of the radius. 

Insertion. 

Into the base of the first metacarpal bone. 
Nervous Supply. 

The posterior interosseous nerve. 

Extensor Primi Internodii Pollicis. 
Origin. 

1. From the posterior surface of the radius below 
the foregoing muscle. 

2. From the posterior surface of the interosseous 
membrane. 

Insertion. 

Into the base of the first phalanx of tjie thumb. 
Nervous Supply. 

The posterior interosseous nerve. 

Extensor Secundi Internodii Pollicis. 
Origin. 

1 . From the middle of the outer half of the posterior 
surface of the shaft of the ulna. 

2. From the posterior surface of the interosseous 
membrane. 

Insertion. 

Into the base of the last phalanx of the thumb. 
Nervous Supply. 

The posterior interosseous nerve. 

Extensor Indicis. 
Origin. 

1. From the posterior surface of the shaft of the 
ulna below the foregoing muscle. 

2. From the posterior surface of the interosseous 
membrane. 

Insertion. 

This tendon joins with the tendon of the extensor 
communis digitorum. The common tendon, so formed, 
is inserted into the bases of the 2nd and 3rd phalanges 
of the index finger. 
Nervous Supply. 

The posterior interosseous nerve. 



MUSCLES OF THE FOREARM. 



289 



ACTION OF THE MUSCLES OF POSTERIOR SUR- 
FACE OF FOREARM. 

The muscles situated upon the posterior surface of the fore- 
arm may be thus classified, as to their action. 



Action. 



•Bg 



'Superficial lay- 
er 






(7) 



.Deep layer. ... (5) 



r Supinator longus 

Extensor carpi rad. longior 

Extensor carpi rad. brevior 

Extensor communis digitorum.. 

Extensor minimi digiti 

Extensor carpi ulnaris . . . . 

Anconeus .... 

Supinator brevis 

Extensor ossis metacarpi pollicis. 
Extensor primi internodii pollicis 
Extensor sec. internodii pollicis. 

k Extensor indicis 




Supinators(2) 



Extensors of 
fingers, (3) 

Extensors of 

hand, (3) 

Extensor of 

forearm, (1) 



Extensors of 
thumb, (3) 



From the above table it is seen that of the 12 muscles on the 
posterior surface of the forearm, 

One extends the forearm. 
Two supinate the hand. 
Three extend the hand. 
Three extend the fingers. 
Three extend the thumb. 
All the pronators and supinators are inserted into the radius, 
principally on its outer border. 

NERVOUS SUPPLY OF THE MUSCLES OF THE POS- 
TERIOR SURFACE OF THE FOREARM. 

All the posterior muscles of the forearm are supplied with 
nerve power from the musculo spiral nerve or its interosseous 
branch. 



ACTION OF THE MUSCLES OF THE FOREARM IN 

GENERAL. 

The action of the muscles of the forearm will be considered, in 
detail, later on in connection with the muscles of the hand. 

The muscles on the anterior surface of the forearm are flexors 



290 



MYOLOGY. 



and pronators in their action, while those on the posterior surface 
perform the functions of extension and supination. 

They may, however, be here enumerated under the following 
heads : 

f The supinators (2) 

A. Muscles acting upon the hand as J The pronators (2) 

a whole (10) 1 The flexors of the wrist, (3) 

[ The extensors " " (3) 

B. Muscles acting on the fingers in i The flexors (2) j ^ofundus d lgitTmm. 

common (3) ) ; fa 

I The extensor.. . (i)-{ Communis digitorum. 

(Thumb (3) 

C. Extensors of special fingers (5) ■< Little finger. ... (1) 

(index " .... (1) 

D. Flexors of special fingers = (i)-{ Flexor longus pollicis. 

E. Extensor of forearm (i)«j Anconeus. 

GENERAL NERVOUS DISTRIBUTION TO THE 
FOREARM. 

The nervous supply to the muscles of the forearm, considered 
as a whole, is as follows : 

To the anterior surface. .(8 muscles.) \ ™ e m f an nerve su P? lies 6 f musc ! eS - 

v ' I 1 he ulnar nerve supplies. .......... r| muscles. 

^p ., , . . f 1 n in \ The interosseous nerve supplies . .,. .Q muscles. 

10 the posterior surface (12 muscles.) ■< -., ; , . , v Z -i 

r v ' (i he musculo- spiral nerve supplies.. .3 muscles. 

Total, 20 

GENERAL SUMMARY OF THE MUSCLES OF THE 

FOREARM. 

All the flexors and extensors of the wrist are inserted into the 
base of a metacarpal bone, except the palmaris longus muscle. 

Of the twenty muscles of the forearm, all except one, the 
anconeus, act directly or indirectly upon the hand. 

Of these twenty muscles, fifteen cross the wrist joint, and the 
remaining five, the anconeus, 2 pronators and 2 supinators, are 
inserted into the bones of the forearm. Of these fifteen muscles 
which cross the wrist joint, six cross in front and nine cross pos- 
teriorly to the joint. The position of the tendons is shown in the 
following table : 

The flexor tendons of the fingers and of the thumb pass, at 
the wrist joint, through a large synovial sheath, which is situated 
underneath the annular ligament and which extends upwards for 
a space of about one and a half inches in the forearm, and down- 
wards to the centre of the palm. This synovial sheath communi- 
cates with the separate sheaths of the thumb and the little finger 
but does not communicate with those of the other fingers. 



MUSCLES OF THE HAND. 



291 



Upon the back of the wrist the extensor muscles of the thumb 
have the longest sheaths, although those of the other tendons are 
seldom less than two inches in length. A peculiar crepitus called 
" tenalgia crepitans " is produced by a local inflammation of the 
synovial sheaths of these tendons, which is produced by excessive 
and rapid use of the fingers. 



Tendons crossing the wrist joint. 



(I5H 



In front... (6) 



I Behind. 



r 3 in grooves. 
3 above the grooves, ly- 
ing superficial to the 
annular ligament of 
the wrist, 
f 3 canals, each enclosing 
, x J 2 tendons. 

I 3 canals, each enclosing 
I I tendon. 



D. 



MUSCLES OF THE HAND. 



The muscles of the hand are 19 in number and may be ar- 
ranged in three groups, as follows : 

f Abductor pollicis. 
(A.) Radial group, forming " thenar eminence" or the J Opponens pollicis. 

" ball of the thumb!' . . , 4 muscles. 1 Flexor brevis pollicis. 

[Adductor pollicis. 

f Palmaris brevis. 
(B.) Ulnar group, forming the " hypothenar eminence." J Abductor minimi digiti. 

4 muscles. j Flexor minimi digiti. 

[Opponens minimi digiti. 

4 lumbricales. 
(C.) Palmar group 11 muscles. \ n • T , fprncc ^ j 3 palmar (abductors.) 



7 mterossei. 



4 dorsal (adductors.) 

The "opponens" muscles of the thumb and little finger are 
called also " flexor ossis metacarpi," when spoken of by some 
anatomists, since that name also indicates their action. 



ORIGIN AND INSERTION. 



RADIAL GROUP. 

(4 muscles). 



Abductor Pollicis. 



Origin. 



1. Ridge on the anterior surface of the trapezium. 

2. From the anterior annular ligament o( the wrist. 



292 MYOLOGY. 

Insertion. 

Into the outer or radial side of the base of the first 
phalanx of the thumb. 
Nervous Supply. 

The median nerve. 

Opponens Pollicis. 
Origin. 

1. From the anterior surface of the trapezium. 

2. From the annular ligament of the wrist. 
Insertion. 

Into the whole length of the outer border of the 
metacarpal bone of the thumb. 
Nervous Supply. 

The median nerve. 

Flexor Brevis Pollicis. 
Origin. 

Outer or superficial head. 

1. From the trapezium. 

2. From the annular ligament. 
Inner or deep head. 

1. From the trapezoid bone. 

2. From the os magnum. 

3. From the 2nd and 3rd metacarpal bones. 
Insertion. 

Into either side of the base of the first phalanx of 
the thumb, (a sesamoid bone being frequently found 
in each tendon.) 
Nervous Supply. 

The median nerve to the outer half, and the ulnar 
nerve to the inner half of the muscle. 

Adductor Pollicis. 
Origin. 

From the lower two-thirds of the anterior surface 
of the third metacarpal bone. 
Insertion. 

Into the inner side of the base of the first phalanx 
of the thumb. 
Nervous Supply. 

The ulnar nerve. 



MUSCLES OF THE HAND, 



B. 



293 



ULNAR GROUP. 

(4 muscles). 

Palmaris Brevis. 
Origin, 

From the annular ligament and the central palmar 
fascia. 
Insertion, 

Into the integument over the inner border of the 
hand. 
Nervous Supply. 

The ulnar nerve. 

Abductor Minimi Digiti. 
Origin. 

1. From the pisiform bone. 

2. Slightly from the tendon of the flexor carpi 
ulnaris. 

Insertion. 

Into the inner side of the base of the first phalanx 
of the little finger. 
Nervous Supply. 

The ulnar nerve. 

Flexor Mimimi Digiti. 
Origin* 

1. From the unciform process of the unciform bone. 

2. From the annular ligament. 
Insertion. 

Into the inner side of the base of the first phalanx 
of the little finger. 
Nervous Supply. 

The ulnar nerve. 

Opponens or Adductor Minimi Digiti. 
Origin. 

1. From the unciform process of the unciform bone. 

2. From the annular ligament. 
Insertion. 

Into the whole length of the inner border of the 
metacarpal bone of the little finger. 
Nervous Supply. 

The ulnar nerve. 



294 



MYOLOGY. 

c. 

PALMAR GROUP. 

LUMBRICALES. 

Origin. 

The first and sometimes the second lumbricales 
arise from the outer side of the corresponding tendon 
of the flexor profundus digitorum. 

The third and fourth lumbricales arise, respectively, 
from adjoining sides of the 2d and 3d, and the 3d and 
4th tendons of the deep flexor. 
Insertion. 

Into the outer side of the expansions of the corre- 
sponding extensor tendons on the back surface of the 
first phalanges. 
Nervous supply. 

Branches of the ulnar nerve to the two inner, and 
of the median nerve to the two outer muscles. 

Interossei Muscles. 

The interossei muscles, like the lumbricales, are named in 
numerical order from the radial towards the ulnar side of the 
hand. They are seven in number and consist of two sets, viz., 
a palmar set (3) and a dorsal set (4). 

A. Palmar Interossei, (Three in number). 
Origin. 

From the whole length of one side of a metacarpal 
bone of one finger. 
Insertion. 

Into the same side of the base of the first phalanx 
of the same finger and into the expansions of the ten- 
don of the extensor muscle of that finger. 
Nervous supply. 

The deep palmar branches of the ulnar nerve. 

B. Dorsal Interossei, (Four in number). 
Origin. 

Each muscle arises by two heads from the adjacent 
sides of the two metacarpal bones between which it 
is situated, but most extensively from that one which 
supports the finger on which the muscle acts. 



MUSCLES OF THE HAND. 



295 



Insertion. 

1. Into the corresponding side of the base of the 
first phalanx of that finger, which lies in a direct line 
from the most extensive point of origin. 

2. Into the expansion of the extensor tendon which 
covers that finger. 

Nervous supply. 

The deep palmar branches of the ulnar nerve. 

ACTION OF THE MUSCLES OF THE HAND. 

The muscles of the hand may be arranged according to their 
action as follows; the total number of muscles acting upon each 
finger being shown, as well as the special action of each muscle 
forming those totals. 



1 

Digits. 


Flexors. 


Adductors. 


Abductors. 


Total. 


Acting on thumb 

" " 2nd finger.. 

" 3rd " 
" 4th 
" 5th 
" " integument. 


2 
1 
1 
1 
3 






4 
3 
3 
3 
5 
1 




Total 


8 


.■ | 5 


19 



NERVOUS SUPPLY OF MUSCLES OF THE HAND. 



f Abductor pollicis. 
I Opponens pollicis. 

The median nerve supplies 4-3- muscles.^ 1st lumbricalis. 

2nd lumbricalis. 

Outer half of Flexor brevis pollicis 
f Palmaris brevis. 
Abductor minimi digiti. 
Flexor minimi digiti. 
Opponens minimi digiti. 

The ulnar nerve supplies 14^ muscles. \ Adductor pollicis. 

— 3rd lumbricalis. 

Total, 19 4th lumbricalis. 

7 interossei muscles. 
Jlnnerhalfot Flexor brevis pollicis 



296 



MYOLOGY. 



Table Illustrating the Distribution of the Motor Nerves of the Mus- 
cles which Act upon the Hand and Fingers. 







Name of the Nerve. 




Region 


Supplied. 


Musculo- 

spiral 
and branch. 


Median. 


Ulnar. 


Total. 


Forearm. . . . < 
Hand, ] 


Anterior surface. 
Posterior surface. 


II 


6* 


1* 


8 
11 






Anterior surface. 
Posterior surface. 




4* 


14$ 


19 














11 muscles. 


11 muscles 


16 muscles. 


38 muscles. 







POINTS OF SPECIAL INTEREST PERTAINING TO 
THE UPPER EXTREMITY IN GENERAL. 

The insertions of the 19 muscles of the hand may be thus sim- 
plified : 

16 are inserted into the first phalanges. 
2 " " metacarpal bones. 

lis " " the integument of hand. 

19 

In animals, as the type descends from that of man, the digits 
disappear in the following order : 

The 1st digit. 
" 5th " 
" 2nd " 
" 4th " 

« 3rd « 

The height of the individual is usually equal to the distance 
between the tips of the middle fingers when the arms are ex- 
tended. 

The hand is capable of six distinct movements, viz. : prona- 
tion, supination, flexion, extension, abduction and adduction. 



MUSCLES OF THE HAND. 



2 97 



Pronation of the hand is performed by. .(2) muscles, j ^^V^rlt^ a " d pr ° na " 



Supination 



Extension 



Flexion 



Adduction 



Abduction 



" .-(2) 
" ..(3) 

" -.(3) 

" ..(2) 

..(3) 



j Supinator longus and supinator 
( brevis. 

i Extensor carpi radialis longior. 
Extensor carpi radialis brevior. 
Extensor carpi ulnaris. 

I Flexor carpi radialis. 
■< Palmaris longus. 
( Flexor carpi ulnaris. 

( Flexor carpi ulnaris. 
I Extensor carpi ulnaris. 

Flexor carpi radialis. 
Extensor carpi radialis longior. 
Extensor carpi radialis brevior. 



The 38 muscles which act upon the hand, (comprising all the 
muscles of the forearm excepting one, the anconeus, and those of 
the hand itself,) may be arranged in four classes, as follows : 

1st. Those which act upon the hand as a whole, 10 
2nd. " " " " " fingers in common. 3 

3rd. " " " " " separate fingers, 24 



4th. 



integument , 



38 



In order to more clearly elucidate the action of each of these 
muscles, the following table has been prepared : 

Table of Muscles acting upon the Hand. 



Part acted upon. 


Prona- 
tors. 


Supina- 
tors. 


Flexors 


Exten- 
sors. 


Adduc- 
tors. 


Abduc- 
tors. 


Total 

Muscles. 


1 

Total 
Tendons. 


Hand as a whole. . 
Fingers in common 
Thumb alone 


2 


2 


3 
2 

3 

1 
1 
3 


3 

1 

3 
1 

1 






10 

3 
8 

4 
3 
3 
6 
1 


10 

8 

7 
6 
6 

9 
» 1 






I 
1 
I 
I 
I 




Index finger alone. 






Middle " 
Ring " " 
Little " 
Integument 






























Total .... 


2 


2 


14 


9 


5 


6 


3S 


47 



The number of tendons specified as belonging to each digit ex- 



298 



MYOLOGY. 



cept in the thumb, represents the number of muscles acting 
upon it singly, in addition to the tendons of the three muscles 
acting in common upon the fingers. 



Table of the Muscles Divided in Amputatation at any 
of the Joints of the Upper Extremity. 



Muscles passing over 
two Joints. 



1 Sterno-cleido-mas- 1 

toid. 

2 Sterno-hyoid. 

3 Omo-hyoid. 



1 Pectoralis major. 

2 Latissimus dorsi. 



1 Biceps flexor cubiti. 

2 Triceps exten. cubiti 

1 Flexor carpi radialis 

2 Palmaris longus. 

3 Flexor sublimis dig. 

4 Flexor carpi ulnaris. 

5 Extensor car. radial- 

is longior. 

6 Ex. carpi rad. brev. 

7 Extensor communis 

digitorum. 

8 Extensor min. digiti 

9 Extensor carpi ulna- 



HEAD AND NECK 




Total, 25 



Muscles passing over 
one joint. 



1 Subclavius. 

2 Pectoralis minor. 

3 Serratus magnus, 
J 4 Trapezius. 

5 Levator anguli scap- 
ulae. 

6 Rhomboideus minor. 

7 Rhomboideus major. 

1 Deltoid. 
■z Supra-spinatus. 

3 Infra-spinatus. 
- 4 Teres minor. 

5 Teres major. 

6 Subscapularis. 
w 7 Coraco-brachialis. 

f 1 Brachialis anticus. 
I 2 Pronator radii teres. 
\ 3 Anconeus. 

4 Supinator longus. 
[ 5 Supinator brevis. 

f 1 Flexor long, pollicis. 

2 Flexor profund. dig. 
, 3 Ex. ossis meta. pol. 

1 4 Ex. primi. int. pol. 

5 Ex. sec. int. pollicis. 
I 6 Extensor indicis. 



In this table four knives are represented as placed succes- 
sively between the trunk and shoulder joints ; the shoulder and 
the arm ; the arm and forearm ; and the forearm and hand ; thus 
indicating the amputations to be performed. 

On one side of the knives, are arranged the number of muscles 
crossing one joint, and, on the other side, the number of muscles 
crossing two joints, before their insertion into a bone. 

The lines crossing the blade of the knife indicates the sets of 
muscles divided ; and the numbers at the extremity of those lines 
indicate the total of each of these sets of muscles. 

As an example, the first knife makes an imaginary amputation 
between the trunk and the shoulder, thus removing the scapula 
and the clavicle. 

The blade is crossed by three lines, indicating that three sets of 
muscles are divided. These lines, if traced to their termination, 
disclose the three sets of muscles to be as follows : 



MUSCLES OF UPPER EXTREMITY. 299 

(1) Those connecting the head to the shoulder, passing over two joints, 3 muscles. 

(2) " " " trunk to the arm, " " " " 2 " 

(3) " " trunk to the shoulder, " " one joint, 7 " 

Total, 12 « 

The second knife indicates an amputation between the shoul- 
der and the arm, (or at the shoulder-joint). The three lines cross- 
ing the blade indicate a total of 1 1 muscles' divided if the numbers 
corresponding to each of these lines be added together. 

MUSCLES OF THE UPPER EXTREMITY. 
GENERAL SUMMARY. 

In the upper extremity, the 62 muscles may be thus enum- 
erated, in closing. 

1. Muscles passing over two joints before insertion, 16 

2. Muscles passing over one joint before insertion, 25 

3. Muscles passing over no joint before insertion, 2 

4. Muscles of the hand, 19 



Total, 62 

Nervous supply. 

The 50 intrinsic muscles of the upper extremity are thus sup- 
plied with nerves. 

By the ulnar nerve, are supplied 16 muscles. 

By the musculo-spiral nerve, are supplied 14 muscles. 

By the median nerve, are supplied 1 1 muscles. 
.By the musculocutaneous tierve, are supplied 3 muscles. 

By the circumflex nerve, are supplied 2 muscles. 

By the sub-scapular nerve, are supplied 2 muscles. 

By the supra-scapular nerve, are supplied 2 muscles. 



Total, 50 

These muscles will be found classified both as regards their 
situation and their nervous supply in the following table. 



300 MYOLOGY. 

Nervous Supply of the Extrinsic Muscles of the 
Upper Extremity. 

Name of Nerve. Name of Muscle. 

___-—— ^* Sterno-mastoid. 
Cervical plexus *^ -"""" / . Sternohyoid. 

(deep branches.) \^^^ / / 

Long subscapular. . . . '^\^*^>^C^/0 Sterno-thyroid. 

X^^^T^^^ Trapez I us « 

Spinal accessory s^ /y\ ^^* Latissimus dorsi. 

5th Cervical nerve 3 ^^ » Rhomboideus major. 

Descendens noni. . . ) / ^^^^TnT^* Rhomboideus minor. 
Communicans noni. ( 3< N. ^^~^\\ 

\ ^* Levator anguli scapula. 

Anterior thoracic g~ ^^N. . Pectoralis major. 

Posterior thoracic . . . . ,^ -^ Pectoralis minor. 

SUBCLAVIUS. 
SERRATUS MAGNUS. 

Total, 15 
Deduct muscles with 
two sources of supply, 3 

12 12 muscles. 

The twelve extrinsic muscles, as shown above, are thus sup- 
plied with nerve power. 

The anterior thoracic nerve supplies 2 muscles. 

The posterior thoracic nerve supplies I muscle. 

The subscapular nerve supplies 2 muscles. 

The $th cervical nerve supplies 3 muscles. 

The spinal accessory nerve supplies I muscle. 

The descendens noni nerve ) ,. 1 

~. . . ^supplies 3 muscles. 

The communicans noni nerve ) 

Total, 12 

Action of Muscles upon the Scapula. 
The scapula is moved 

{Trapezius. 
Levator anguli scapulae. 
Rhomboideus minor and major. 
C Lower part of trapezius. 

• Downwards by •< Latissimus dorsi. 

( Pectoralis minor. 

Forwards by \ P ect ° ralis minor - 

J ( Serratus magnus. 

C Trapezius. 

Backwards by ■< Rhomboideus minor and major. 

( Latissimus dorsi. 



JPPER EXTREMITY, 



SuPRA-ScAPUL tus> and Infra-spinati 



Subscapular 
Circumflex , 
Musculo-Spir 

Post 



MUSCLES, 



is, and Teres Major. 
d Teres Minor, 
nconeus, Subanconeus, 
[is Longior. 

rpi Radialis Brevior. 
om munis Digitorum. 

nimi Digiti. 
arpi Ulnaris. 



Supinator Longus, and Extensor Carpi 

Supinator Brevis. 

Extensor Ossis Metacarpi Pollicis. 

" Primi Internodii Pollicis. 

" Secundi Internodii Pollicis. 



and Extensor Indicis. 



Musculo-Cut. 



Median Ex. a... „, 

in 1 eres. 



lialis, Biceps, and Brachialis Anticu 

I 



pi Radialis. 

jongus. 

limis Digitorum. 



Ante 



Abductor Pollicis. 
Opponens Pollicis. 
First and Second Lumbricales. 
i of the Flexor Brevis Pollicis (outer 
head). 



ladratus, Flexor Longus Pollicis and outer half of the Flexor 
as Digitorum. 

ulnar, Inner j->j Ulnaris, and inner half of the Flexor Profundus Digitorum. 
Superfici revis _ 

Deep P^>ollicis, Abductor Minimi Digiti. Flexor Brevis Minimi Digiti, 
lens Minimi Digiti, 3d and 4th Lumbricales, the 7 Interossei, 
iuter half of the Flexor Brevis Pollicis (inner head). 



N-B/tes at the same time the name and number of the muscles situated 
on the diffdj-jg anterior, while the Extensor and Supinator Muscles are situa- 
ted on the jL m an( j ] ianc | (27 in number), 11 are supplied by the Median, and 
10 by the \ ie( \ by t| ie Musculo-Spiral, and the remaining 9 by the Posterior 
Interosseoi 



MOTOR NERVES OF THE INTRINSIC MUSCLES OF THE UPPER EXTREMITY. 



Circumflex 
Musculo-Spi 



5 th and 6th 
Cervical 
Nerve. 

From Posterior 

Cord of the 
Brachial Plexus. 



Musculo-Cutanbous, Ex. Cord 
Median, Ex. and In. Cord ... 



Anterior Interosseous 



Ulnar, Inner Cord ... 
Superficial Palmar 
Deep Palmar ... 



Muscles of the 

Scapulo-Humer 

Region or Muscle 

:onnecting the Ai 

with Shoulder. 



Humeral Region 

Muscles situated i 

the Arm. 



Muscles of the 



Supra-spinatus, and Infra-spinatus 



Subscapularis, and Teres Major. 
Deltoid, and Teres Minor. 
Triceps, Anconeus, Subanconeus, 

Radialis Longior. 
Extensor Carpi Radialis Brevior. 

' ' Communis Digitorum. 

" Minimi Digiti. 

" Carpi Ulnaris. 



Supinator Longus, and Extensor Carf 

Supinator Brevis. 

Extensor Ossis Metacarpi Pollicis. 

Primi Internodii Pollicis. 

Secundi Internodii Pollici: 



idicU 



Coraco-Brachialis, Biceps, and Brachialis Ant 



Pronator radii Teres. 
Flexor Carpi Radialis 
Palmaris Longus. 
Flexor Sublimis Digit 

Pronator Quadratus 
Profundus Digil 



Abductor Pollicis. 
Opponens Pollicis. 
First and Second Lumbricales. 
$ of the Flexor Brevis Pollicis (or 
I head). 

Flexor Longus Pollicis and outer half of the Fie 



Flexor Carpi Ulnaris, and 
Palmaris Brevis. 



half of the Flexor Profundus Di; 



Adductor Pollicis, Abductor Minimi Digiti. Flexor Brevis Minimi 
Opponens Minimi Digiti, 3d and 4th Lumbricales, the 7 Ii 
and 'outer half of the F'lexor Brevis Pollicis (inner head). 



Digiti, 



fhTfT - ' 1 * 16 ahove laljle . constructed for the purpose of showing the Motor Nerves of the Intrinsic Muscles of the Upper Extremity, indicates at the same time the name and number of the muscles situated 
n le different segments of the limb. It should be borne in mind that the Flexors and Pronators of the forearm and hand are situated on the anterior, while the Extensor and Supinator Muscles are situa- 
16 by th n StCr v r surface ? f the limb - B y reference to the table, it will also be found that, of the muscles of the anterior surface of the forearm and hand (27 in number), II are supplied by the Median, and 
[ nle jL e nar ,^' rve an d its branches ; and of the muscles of the posterior surface of the forearm and hand (11 in number), 2 are supplied by The Musculo-Spiral, and the remaining 9 by the Posterior 
sseous. The Brachialis Amicus usually receives a filament from the Musculo-Spiral, as well as from the Musculo-Cutaneous Nerve. 



MUSCLES OF UPPER EXTREMITY. 



301 



Action of Muscles upon the Arm. 



The humerus is moved by 



Forwards by. 



Backwards by. 



f Coraco-brachialis. 
J Part of the deltoid, 
j " " pectoralis major, 
[ Assisted by the biceps. 
' Part of the deltoid. 

Teres major. 
" minor. 

Long head of triceps. 

Latissimus dorsi. 



Inwards bv \ Part ° f P ectoralis ma J or - 

inwards by -j Latissimus dorsi> 



Rotated inwards by.. 



Rotated outwards by 



f Subscapularis. 
J Assisted by pectoralis major. 
*| " •' latissimus dorsi. 

(^ " " teres major. 

!Supra-spinatus. 
Infra-spinatus. 
Teres minor. 



Action of Muscles upon the Forearm. 



The forearm is 



Biceps. 

Brachialis anticus. 
Pronator teres. 

Flexed by. \ Asssisted by flexor carpi radialis. 

" " " sublimis digitorum. 

" " carpi ulnaris. 
" " supinator longus. 

******.. .j& 

Pronator teres. 
Flexor carpi radialis. 
Rotated inwards by ... -^ Palmaris longus. 

Flexor sublimis digitorum. 
Pronator quadratus. 

5 Biceps. 
Supinator brevis. 
Extensor secundi internodii pollicis. 



302 



MYOLOGY. 



MUSCLES OF THE LOWER EXTREMITY. 



The muscles of the lower extremity are 60 in number and may 
be arranged in five groups, as follows : 

A. Muscles of the Iliac region, 3 

B. " " femoral region, 24 

C. " " POPLITEAL region, 1 

D. " " CRURAL region, 12 

E. " " PEDAL region, 20 

Total 60 



MUSCLES OF ILIAC REGION. 

This group includes the three following muscles : 
Psoas Parvus. 
Psoas Magnus. 
Iliacus. 

ORIGIN AND INSERTION OF THE MUSCLES OF 
THE ILIAC REGION. 

Psoas Parvus. 
Origin. 

1. From the sides of the bodies of the last dorsal 
and the first lumbar vertebrae. 

2. From the corresponding intervertebral substance. 
Insertion. 

Into the ilio-pectineal eminence. 
Nervous Supply. 

The anterior branches of the lumbar nerves. 

Psoas Magnus. 
in. 



1. From the bases of the transverse processes of the 
lumbar vertebrae. 

2. By five slips, from the sides of the bodies of the 
last dorsal and all the lumbar vertebrae and from the 
corresponding intervertebral substances. 

Insertion. 

Into the lesser trochanter of the femur. 
Nervous Supply. 

The anterior branches of the lumbar nerves. 



MUSCLES OF LOWER EXTREMITY. 



303 



ILIACUS. 
Origin, 

1. From the iliac fossa and the inner lip of the crest 
of the ilium. 

2. From the ilio-lumbar ligament. 

3. From the base of the sacrum. 

4. From the anterior superior and the anterior in- 
ferior spines of the ilium, and from the notch between 
them. 

5. From the capsule of the hip joint (a few fibres.) 
Insertion, 

1. Into the lesser trochanter of the femur, in com- 
mon with the tendon of the psoas magnus muscle. 

2. Into a line running from the lesser trochanter to 
the linea aspera. 

Nervous Supply. 

An intra-pelvic branch of the anterior crural nerve. 

ACTION OF THE MUSCLES OF THE ILIAC REGION. 

The iliacus and psoas magnus muscles are powerful flexors 
of the thigh, if the fixed point during their action be the pelvis 
and the vertebral column. They also rotate the thigh outzvards 
after flexion has been performed, on account of the obliquity of 
their insertion into the femur. If the fixed point during their 
action, however, be below their point of origin, these muscles 
tend to bend the pelvis and the lumbar vertebroe forward. In 
raising the trunk, when the body is in a recumbent position, these 
muscles become, therefore, powerful agents. 

These two muscles tend also to assist in maintaining an erect 
position of the body, by supporting the spine and the pelvis upon 
the femur. 

The psoas parvus is a simple tensor of the iliac fascia. 

NERVOUS SUPPLY OF THE MUSCLES OF THE 
ILIAC REGION. 

These muscles are all supplied by branches of the lumbar 
plexus, though the iliacus muscle is indirectly so supplied by an 
intrapelvic branch of the anterior crural nerve. 



304 



MYOLOGY, 



B. 



MUSCLES OF THE FEMORAL REGION. 

The muscles included in this group are 24 in number and may 
be arranged in four groups. 



(1) The anterior femoral group 



Tensor vaginae femoris. 
SarLorius. 
Rectus femoris. 
.7 muscles.^ Vastus externus. 
Crureus. 
Vastus internus. 
Sub-crureus. 



f Gracilis. 
I Pectineus. 

(2) The internal femoral group : 5 muscles.^ Adductor longus. 

I Adductor brevis. 
(_ Adductor magnus. 

f Gluteus maximus. 
Gluteus minimus. 
Gluteus medius. 
Pyriformis. 

(8) Tte gluteal ox posterior superior group:... .9 muscles. \ Gemellus superior. 

Obturator internus. 

Gemellus inferior. 

Obturator externus. 

__ Quadratus femoris. 

Biceps flexor cruris. 

(4) The posterior femoral group : 3 muscles, -j Semitendinosus. 

Semimembranosus. 



ORIGIN AND INSERTION OF THE MUSCLES OF 
THE FEMORAL REGION. 

1. ANTERIOR FEMORAL GROUP. 

(7 muscles.) 

Tensor Vaginae Femoris. 
Origin. 

1. From the anterior superior spine of the ilium. 

2. From the anterior portion of the outer lip of the 
crest of the ilium. 

Insertion. 

Into the fascia lata, on the outer aspect of the thigh. 
Nervous supply. 

The superior gluteal nerve. 

Sartorius. 
Origin. 

1. From the anterior superior spine of the ilium. 

2. From the upper half of the notch below it. 



MUSCLES OF LOWER EXTREMITY, 305 

Insertion, 

Into the upper part of the inner surface of the shaft 
of the tibia, covering the tendons of the gracilis and 
the semitendinosus. 
Nervous supply. 

The anterior crural nerve. 

Rectus Femoris. 
Origin. 

Straight tendon. From the anterior inferior spine 

of the ilium. 
Reflected tendon. From a groove above the brim of 
the acetabulum. 
Insertion. 

Into the upper border of the patella. 
Nervous supply. 

The anterior crural nerve. 

Vastus Externus. 
Origin, 

1. From the anterior border of, and a ridge upon 
the greater trochanter of the femur. 

2. From a rough line extending from the greater 
trochanter to the linea aspera. 

3. From a line from the linea aspera to the outer 
condyle. 

4. From the whole length of the linea aspera (outer 

up). 

5. From the inter-muscular septum. 
Insertion. 

Into the outer border of the patella. 
Nervous supply. 

The anterior crural nerve. 

Vastus Internus. 
Origin. 

1. From a line running from the inner side of the 
neck of the femur to the linea aspera. 

2. From the whole length of the linea aspera 
(inner lip). 

3. From a line from the linea aspera to the innei 
condyle. 

4. From the inner surface of the femur. 

5. From the inter-muscular septum. 



3 o6 MYOLOGY. 

Insertion. 

Into the inner border of the patella. 
Nervous supply. 

The anterior crural nerve. 

Crureus. 
Origin. 

From the anterior and outer surfaces of the middle 
third of the femur. 
Insertion. 

Into the upper border of the patella, in common 
with the tendon of the rectus and vasti muscles. 
Nervous supply. 

The anterior crural nerve. 
This muscle, with the three succeeding muscles, are sometimes 
considered as forming one muscle, which is called the quadriceps 
extensor muscle of the thigh. 

SUB-CRUREUS. 
Origin. 

From the lower part of the anterior surface of the 
femur. 
Insertion. 

Into the upper pouch of the synovial membrane of 
the knee joint. 
Nervous supply. 

The anterior crural nerve. 

INTERNAL FEMORAL GROUP. 

(5 muscles.) 

Gracilis. 
Origin. 

1. From the inner margin of the rami of the pubes 
and the ischium. 

2. From the body of the pubes (lower half). 
Insertion. 

I. Into the upper part of the inner surface of the 
shaft of the tibia, above the point of insertion of the 
semitendinosus muscle. 
Nervous supply. 

The obturator nerve. 
Pectineus. 



Origin. 



From the ilio-pectineal line, and the surface of bone 



MUSCLES OF LOWER EXTREMITY. 



307 



in front of it, extending from the pectineal eminence to 
the spine of the pubis. 
Insertion. 

1. Into the upper part of the line running from the 
lesser trochanter of the femur to the linea aspera. 

2. Into the femur behind the lesser trochanter. 
Nervous supply. 

The obturator nerve, and often the anterior crural 
and the accessory obturator nerves. 

Adductor Longus. 
Origin. 

From the anterior surface of the pubes, close to its 
angle and below its crest. 
Insertion. 

Into the middle third of the inner lip of the linea 
aspera, between the vastus internus and the adductor 
magnus muscles. 
Nervous supply. 

The obturator nerve. 

Adductor Brevis. 
Origin. 

From the anterior surface of the body and the 
ramus of the pubes. 
Insertion. 

Into the upper part of the linea aspera, behind the 
pectineus and the upper part of the adductor longus 
muscles. 
Nervous supply. 

The obturator or anterior crural nerve. 

Adductor Magnus. 
Origin. 

1. From the descending ramus of the pubes (lower 
part.) 

2. From the ascending ramus of the ischium. 

3. From the outer side of the tuberosity of the 
ischium. 

Insertion. 

1. Into the whole length of the linea aspera. 

2. Into a line running from the linea aspera to the 
inner condyle of the femur. 

3. Into a tubercle above the inner condyle of the 
femur. 



308 MYOLOGY. 

Nervous supply. 

The obturator nerve. 

GLUTEAL OR POSTERIOR SUPERIOR GROUP. 

(9 muscles). 

Gluteus Maximus, 
Origin. 

1. From the dorsum of the ilium, behind the supe- 
rior curved line. 

2. From the sides of the sacrum and of the coccyx. 

3. From a tendinous expansion over the sacrum. 

4. From the posterior surface of the great sacro- 
sciatic ligament. 

Insertion. 

1. Into the fascia lata, covering the outer side of the 
thigh. 

2. Into a line running from the great trochanter of 
the femur to the linea aspera. 

Nervous supply. 

The inferior gluteal nerve. 

Gluteus Medius. 
Origin. 

1. From the dorsum of the ilium, between the supe- 
rior and the middle curved lines. 

2. From the outer lip of a portion of the crest of the 
ilium. 

3. From an aponeurosis covering its anterior surface. 
Insertion. 

Into an oblique line on the outer surface of the 
great trochanter of the femur. 
Nervous supply. 

The superior gluteal nerve. 

Gluteus Minimus. 
Origin. 

1. From between the middle and the inferior curved 
lines of the dorsum of the ilium. 
Insertion. 

Into the anterior border of the greater trochanter 
of the femur. 
Nervous supply. 

The superior gluteal nerve. 



MUSCLES OF LOWER EXTREMITY. 



309 



Pyriformis. 
Origin. 

1. From the anterior surface of the sacrum, be- 
tween the anterior sacral foramina. 

2. From the margin of the great sacro-sciatic fora- 
men. 

3. From the anterior surface of the sacro-sciatic 
ligament. 

Insertion. 

Into the posterior part of the upper border of the 
great trochanter of the femur. 
Nervous supply. 

A muscular branch of the sacral plexus. 

Gemellus Superior. 
Origin. 

From the outer surface of the spine of the ischium. 
Insertion. 

Into the great trochanter of the femur, by a com- 
mon tendon with the obturator internus and the ge- 
mellus inferior muscles. 
Nervous supply. 

A muscular branch of the sacral plexus. 

Obturator Externus. 
Origin,. 

From the inner two-thirds of the outer surface of 
the obturator membrane. 

2. From the circumference of the obturator foramen. 

3. From a fibrous arch over the obturator vessels 
and nerves. 

Insertion. 

Into the digital fossa of the femur. 
Nervous supply. 

The obturator nerve. 

Gemellus Inferior. 
Origin. 

From the upper part of the outer lip of the tuber- 
osity of the ischium. 
Insertion. 

In common with the tendon of the obturator in- 
ternus muscle, into the great trochanter of the femur. 
Nervous supply. 

A muscular branch of the sacral plexus. 



3io myology. 

Obturator Internus. 
Origin. 

1. From the inner surface of the anterior and ex- 
ternal wall of the true pelvis, in the region of the obtur- 
ator foramen. 

2. From the inner surface of the obturator mem- 
brane. 

3. From the fibrous arch covering the obturator 
vessels. 

Insertion. 

Into the upper border of the great trochanter of the 
femur. 
Nervous supply. 

A muscular branch of the sacral plexus. 

Quadratus Femoris. 
Origin. 

From the outer border of the tuberosity of the 
ischium. 
Insertion. 

Into the upper part of the linea quadrati, on the 
posterior aspect of the great trochanter of the femur. 
Nervous supply. 

A muscular branch of the sacral plexus. 

POSTERIOR FEMORAL GROUP. 

(3 muscles). 

Biceps Flexor Cruris. 
Origin. 

Long head. 

1. In common with the tendon of the semitendin- 
osus, from the posterior part of the tuberosity of 
the ischium. 

Short head. 

2. From the whole length of the outer lip of the 
linea aspera, between the adductor magnus and 
the vastus externus muscles. 



Insertion. 



Into the outer side of the head of the fibula, where 
the tendon divides again into two parts for further 
insertion into the outer tuberosity of the tibia and 
the fascia of the leg. 



MUSCLES OF LOWER EXTREMLTY. 



311 



Nervous supply. 

The great sciatic nerve. 

Semi-Tendinosus. 
Origin. 

In common with the long head of the biceps flexor 
cruris, from the inner and lower part of the posterior 
surface of the tuberosity of the ischium. 
Insertion. 

Into the upper part of the inner surface of the shaft 
of the tibia, beneath the sartorius and below the 
gracilis muscle. 
Nervous supply. 

The great sciatic nerve. 

Semi-Membranosus. 
Origin. 

1. From the upper and outer part of the posterior 
surface of the tuberosity of the ischium. 

2. From the outer side of the point of origin of 
the biceps and semitendinosus. 

Insertion. 

1. Into the posterior part of the inner tuberosity of 
the tibia. 

2. Into a groove on the inner tuberosity of the 
tibia (this slip passing under the internal lateral liga- 
ment of the knee). 

3. Into the posterior and outer part of the condyle 
of the femur, thus strengthening the posterior liga- 
ment of the knee-joint. 

Nervous supply. 

The great sciatic nerve. 

ACTION OF MUSCLES OF THE FEMORAL REGION 
UPON THE HIP JOINT. 

The motions of the hip joint may be enumerated as follows : 

Flexion. 

Extension. 

Adduction. 

Abduction. 

External rotation. 

Internal rotation. 
The muscles of the femoral region producing these various 



MYOLOGY. 



312 

motions of the joint are of great interest to the surgeon, and may 
be thus classified, to assist the memory of the student. 



(A.) Muscles producing flexion of the hip joint 



(B.) 



(C) 



(D.) 



(E.) 



(F.) 



extension 



adduction 



abduction 



external rotation 



internal rotation 



'Sartorius (after the leg has 

been flexed.) 
Psoas. 
(6)-j Iliacus. 

I Adductor brevis. 
I Pectineus. 
[Rectus femoris. 
f Gluteus maxhnus. 
I Gluteus medius {posterior half 
of the muscle.) 
Gluteus - minimus {posterior 
(8) \ fifth of the muscle.) 

Pyriformis (to a very slight 

extent.) 
The four ham-string muscles 
(when the leg is extended.) 

{Adductor longus. 
Adductor brevis. 
Adductor magnus. 
Pectineus. 
Gracilis (when leg is extended) 
f Gluteus maximus. 
/ \ j Gluteus medius. 
\4,n Gluteus minimus. 

[ Tensor vaginae femoris. 
'The six muscles of the great 
trochanter (except in the 
sitting posture.) 
The three adductor muscles. 
.. (13)^ Pectineus, 
Psoas. 
Iliacus. 
Sartorius (after the leg has 

been flexed.) 
Tensor vaginae femoris. 
(2-|) -\ Gluteus minimus. 

Gluteus medius (anterior half) 



Of these muscles the two principal flexors lie in front of the 
hip joint and are inserted into the lesser trochanter of the femur. 

The six external rotators lie behind the hip joint and are in- 
serted into the great trochanter of the femur, excepting one, viz., 
the obturator externus. 



MUSCLES OF THE THIGH. 



313 



Through the anterior crural nerve .6 muscles. 



Through the sacral plexus (muscular branches) 5 muscles. 



NERVOUS SUPPLY OF THE MUSCLES OF THE 
FEMORAL REGION. 

The muscles of the femoral region are thus supplied with 
motor power. 

C The 4 muscles forming the 
J quadriceps extensor. 
) Sartorius. 
[Subcrureus. 
C The 3 adductor muscles. 

.uscles.^j obturator externus. 
Gracilis. 
Pyriformis. 
Gemellus superior. 
Obturator internus 
Gemellus inferior. 
^ Quadratus femoris. 
( Biceps. 

Through the great sciatic nerve 3 muscles. •< Semimembranosus. 

( Semitendinosus. 
( Gluteus medius. 

Through the superior gluteal nerve 3 muscles. •< Gluteus minimus. 

( Tensor vagina? femoris. 

Through the small sciatic nerve 1 muscle. \ Gluteus maximus. 

Total, 24 



MUSCLES OF THE POPLITEAL REGION. 

The Popliteus. 
Origin. 

From a groove on the outer side of the internal 
condyle of the femur, situated below the tubercle for 
the attachment of the external lateral ligament of the 
knee" joint. 
Insertion. 

Into a triangular surface on the posterior aspect of 
the upper portion of the tibia, above its oblique line. 
Nerve supply. 

This muscle is supplied with motor power through 
the internal popliteal 'nerve (a branch of the great sciatic). 



314 MYOLOGY. 

D. 

MUSCLES OF THE CRURAL REGION. 

This class of muscles comprises 12 muscles, which may be 
arranged in four groups of three muscles each, as follows : 

{Tibialis anticus. 
Extensor proprius pollicis. 
Extensor longus digitorum. 
( Gastrocnemius. 

(2) " superficial posterior group 3 " •< Plantaris. 

( Soleus. 

( Tibialis posticus. 

(3) " deep POSTERIOR group 3 " ■< Flexor longus pollicis. 

( Flexor longus digitorum. 

{Peroneus longus. 
Peroneus brevis. 
Peroneus tertius. 



ORIGIN AND INSERTION. 

ANTERIOR GROUP. 
(3 muscles). 

Tibialis Anticus. 
Origin. 

1. From the tuberosity of the tibia. 

2. From the upper two-thirds of outer surface of 
the shaft of the tibia. 

3. From the interosseous membrane and the inter- 
muscular septum. 

4. From the deep fascia of the leg. 
Insertion. 

1. Into the inner and under surface of the cuneiform 
bone. 

2. Into the base of the 1st metatarsal bone. 
Nervous supply. 

The anterior tibial nerve. 

Extensor Proprius Pollicis. 
Origin. 

1. From the middle of the anterior surface of the 
shaft of the fibula. 

2. From the interosseous membrane. 
Insertion, 

Into the base of the last phalanx of the great toe. 
Nervous supply. 

The anterior tibial nerve. 



MUSCLES OF THE LEG. 



315 



Extensor Longus Digitorum. 
Origin. 

1. From the tuberosity of the tibia. 

2. From upper three-fourths of the anterior surface 
of the fibula. 

3. From the interosseous membrane. 

4. From the inter-muscular septa. 

5. From the deep fascia of the leg. 
Insertion. 

Into the bases of the second and third phalanges of 
the four outer toes. 
Nervous supply. 

The anterior tibial nerve. 

THE POSTERIOR SUPERFICIAL GROUP. 

(3 muscles). 
Gastrocnemius. 
Origin. 

Inner head. 

1. From a depression at the upper and posterior 
part of the inner condyle of the femur. 

2. Internal division of the linea aspera. 
Outer head. 

1. From a depression in the posterior surface of 
the outer condyle of the femur. 

2. From the external division of the linea aspera. 
Insertion. 

In common with the tendon of the soleus, into the 
lower part of the posterior surface of the os calcis. 
Nervous supply. 

The internal popliteal nerve. 
Plantaris. 
Origin. 

1. From the outer division of the linea aspera. 

2. From the posterior ligament of the knee joint. 
Insertion. 

Into the inner border of the tendo Achillis. 
Nervous supply. 

The internal popliteal nerve. 
Soleus. 
Origin. 

1. From the head and the upper third of the poste- 
rior surface of the fibula. 



316 MYOLOGY, 

2. From the middle third of the internal border of 
the tibia. 

3. From an oblique line on the posterior surface of 
the tibia. 

4. From a tendinous arch, between the tibial and 
fibular points of origin of this muscle. 

Insertion, 

In common with the tendon of the gastrocnemius, 
thus forming the "'tendo Achillis." 
. Nervous supply. 

The internal popliteal nerve. 



THE DEEP POSTERIOR GROUP. 
(3 muscles;. 

Tibialis Posticus. 
Origin. 

1. From the posterior surface of the shaft of the 
tibia. 

2. From the greater part of the posterior surface 
of the interosseous membrane. 

3. From the upper three-fourths of the inner surface 
of the shaft of the fibula. 

4. From the intermuscular fascia. 
Insertion. 

1. Into the tuberosity of the scaphoid bone. 

2. Into the internal and external cuneiform bones. 
Nervous supply. 

The posterior tibial nerve. 

Flexor Longus Pollicis. 
Origin. 

1. From the lower two-thirds of the posterior sur- 
face of the shaft of the fibula. 

2. From the lower part of the interosseous mem- 
brane. 

3. From the intermuscular septum between it and 
the peroneii. 

4. From the fascia covering the tibialis posticus. 
Insertion. 

Into the base of the last phalanx of the great toe. 
Nervous supply. 

The posterior tibial nerve. 



MUSCLES OF THE LEG. 317 

Flexor Longus Digitorum. 
Origin. 

1. From the posterior surface of the shaft of the 
tibia below its oblique line. 

2. From the fascia covering the tibialis posticus. 
Insertion. 

Into the bases of the last phalanges of the four 
outer toes. 
Nervous supply. 

The posterior tibial nerve. 

THE PERONEAL OR LATERAL GROUP. 

(3 muscles). 

Peroneus Longus. 
Origin, 

1. From the head and the upper two-thirds of the 
outer surface of the fibula. 

2. From the anterior and posterior borders of the 
fibula. 

3. From the intermuscular septa. 

4. From the deep fascia of the leg. 
Insertion. 

Into the outer side of the base of the first metatar- 
sal bone. 
Nervous supply. 

The musculo-cutaneous branch of the external po- 
pliteal nerve. 

Peroneus Brevis. 
Origin. 

1. From the lower two-thirds of the outer surface 
of the shaft of the fibula. 

2. From the intermuscular septa between it and the 
muscles of the anterior and posterior groups. 

Insertion. 

Into the base of the fifth metatarsal bone. 
Nervous supply. 

The musculo-cutaneous branch of the external po- 
pliteal nerve. 

Peroneus Tertius. 
Origin. 

I. From the lower one-fourth of the anterior surface 
of the shaft of the fibula. 



318 MYOLOGY. 

2. From the lower part of the interosseous mem- 
brane. 

3. From the intermuscular septum between it and 
the peroneus brevis. 

Insertion. 

Into the base of the fifth metatarsal bone. 
Nervous supply. 

The anterior tibial nerve. 

ACTION OF THE MUSCLES OF THE CRURAL 
REGION. 

The muscles of the crural region, all of which act upon the 
foot, will be found described, in respect to their mode of action, 
in the closing pages of this chapter, since it has been deemed 
more expedient to consider the action of the muscles of the 
crural and pedal region in common, rather than separately. The 
classifications found upon page 324 of this work, will merit the 
earnest perusal and careful study of students in anatomy, since 
their mastery over this difficult subject will thus be rendered com- 
paratively easy. 

NERVOUS SUPPLY OF THE MUSCLES OF THE 
CRURAL REGION. 

The twelve muscles of the crural region receive their nervous 
motor supply from four sources, as follows : 

f Tibialis anticus. 

The anterior tibial nerve supplies 4 muscles. \ ^tensor proprius pollicis. 

rr .hxtensor longus digitorum. 

[ Peroneus tertius. 
Tibialis posticus. 

■posterior tibial " " 3 museles. \ Flexor longus pollicis. 

Flexor longus digitorum. 
Gastrocnemius. 

internal popliteal •' 3 muscles. \ Plantaris. 

Soleus. 

musculo-cutaneous " " 2 muscles. \ ^ , **. ' 

( reroneus brevis. 

Total, 12 muscles. 



(2.) Plantar region. . .19 muscles. 



MUSCLES OF THE FOOT. 379 

E. 

MUSCLES OF THE PEDAL REGION. 

This group of the muscles of the lower extremity embraces 20 
muscles, and may be divided into two sets. 

(1.) Dorsal region , 1 muscle.., , .*<>♦,-{ Extensor brevis digitorum. 

C Abductor pollicis. 
'Superior layer, (3) < Flexor brevis digitorum. 
( Abductor minimi digiti. 
1 -, /„\ ( Flexor accessorius. 

2ndla y er (5)| 4lumbricales> 

( Flexor brevis pollicis. 

3rd layer (4> J Adductor pollicis. 

J J w I 1 ransversus pedis. 

[ Flexor minimi digiti. 

., , / v \ 4 dorsal interoseii. 

U* layer (7) •} J plantar interosseii< 

ORIGIN AND INSERTION. 

DORSAL REGION. 

Extensor Brevis Digitorum. 
Origin. 

1. From the outer and the upper surfaces of the 
greater process of the os calcis. 

2. From the calcaneo-astragaloid ligament. 

3. From the anterior annular ligament of the tarsus. 
Insertion. 

1. Into the first phalanx of the great toe. 

2. Into the outer side of the long extensor tendons 
of the 2d, 3d and 4th toes. 

Nervous supply. 

The external branch of the anterior tibial nerve. 

PLANTAR REGION. 

(19 muscles.) 

FIRST LAYER. 
Abductor Pollicis. 



Origin. 



1. From the greater tuberosity of the os calcis. 

2. From the internal annular ligament of the tarsus. 

3. From the inter-muscular septum between it and 
the flexor brevis digitorum. 



3 20 MYOLOGY. 

Insertion. 

Into the inner side of the base of the first phalanx 
of the great toe. 
Nervous supply. 

The internal plantar nerve. 

Flexor Brevis Digitorum. 
Origin. 

1. From the greater tuberosity of the os calcis. 

2. From the central portion of the plantar fascia. 

3. From the inter-muscular septa on either side. 
Insertion. 

Into the sides of the second phalanges of the four 
outer toes. 
Nervous supply. 

The internal plantar nerve. 

Abductor Minimi Digiti. 
Origin. 

1. From the lesser tuberosity of the os calcis. 

2. From the greater tuberosity, in front of the point 
of origin of the flexor brevis digitorum. 

3. From the inferior surface of the os calcis (to a 
slight extent). 

4. From the plantar fascia and the inter-muscular 
septum between it and the flexor brevis digitorum. 

Insertion. 

Into the outer side of the base of the first phalanx 
of the little toe 
Nervous supply. 

The external plantar nerve. 

SECOND LAYER. 
Flexor Accessorius. 



From the inner and the under surface of the os calcis, 
by two heads which embrace the long plantar ligament. 
Insertion. 

Into the main tendon of the flexor longus digitorum. 
Nervous supply. 

The external plantar nerve. 

LUMBRICALES. 
Origin. 

From the tendons of the flexor longus digitorum, 



MUSCLES OF THE FOOT. 



321 



the innermost from only one, the others from two 
tendons each. 
Insertion. 

Into the inner side of the extensor tendons of the 
toes, and into the inner sides of the bases of the first 
phalanges of the four outer toes. 
Nervous supply. 

The external plantar nerve. 

THIRD LAYER. 

Flexor Brevis Pollicis. 
Origin. 

1. From the adjoining borders of the cuboid and 
the external cuneiform bone. 

2. From an expansion of the tendon of the tibialis 
posticus. 

Insertion. 

Into the inner and outer sides of the base of the 
first phalanx of the great toe. 

A sesamoid bone is frequently developed in each 
tendon of insertion. 
Nervous supply. 

The internal plantar nerve. 

Adductor Pollicis. 
Origin. 

1. From the bases of the 2nd, 3rd and 4th metatar- 
sal bones. 

2. From the sheath of the peroneus longus muscle. 
Insertion. 

Into the outer side of the base of the first phalanx 
of the great toe. 
Nervous supply. 

The external plantar nerve. 

Transversus Pedis. 
Origin. 

1. From the head of the 5th metatarsal bone. 

2. From the transverse ligament of the metatarsus. 
Insertion. 

Into the outer side of the base of the first phalanx 
of the great toe. 
Nervous supply. 

The external plantar nerve. 



322 MYOLOGY. 

Flexor Brevis Minimi Digiti. 
Origin. 

1. From the base of the 5th metatarsal bone. 

2. From the sheath of the peroneus longus muscle. 
Insertion. 

Into the outer side of the base of the first phalanx 
of the little toe. 
Nervous supply. 

The external plantar nerve. 

FOURTH LAYER. 

Plantar Interossei (Three in number). 
Origin. 

1. From the lower or plantar half of the inner side 
of the shafts of the 3d, 4th and 5th metatarsal bones. 
Insertion. 

1. Into the inner sides of the bases of the first pha- 
langes of the toes corresponding to each muscle. 

2. Into the expansion of the corresponding tendon 
of the extensor longus digitorum. 

Nervous supply. 

The external plantar nerve. 

Dorsal Interossei. (Four in number). 
Origin. 

1. From the adjacent sides of two metatarsal bones, 
but most extensively from the bone corresponding to 
the toe of insertion of the muscle. 
Insertion. 

Into the sides of the base of the first phalanx of the 
toe to which they belong. 
Nervous supply. 

The external plantar nerve. 

NFRVOUS SUPPLY OF MUSCLES OF THE FOOT. 

f Abductor pollicis. 

~, . , 7 x7 j t i.\) Flexor brevis pollicis. 

The internal plantar nerve supplies. . (5) j FlexQr brevig £ igitorunli 

[_ Two inner lumbricales. 

„. 1 j.1 * r„,. / T „\ J All the rest of the muscles of the plantar 

The external plantar nerve supplies. (14) < res j on v 

The anterior tibial nerve supplies (i)-{ Extensor brevis digitorum. 

Total, 20 






MUSCLES OF THE FOOT. 



323 



ACTION OF THE MUSCLES OF THE FOOT. 

The action of the various muscles connected with the bones 
of the foot, will be found described in detail in the closing pages 
of this chapter, since it has been found that the action of the 
muscles of the leg and foot can be more clearly understood and 
more easily acquired when considered as a whole, than is practi- 
cable when they are subdivided into special regions. The readers 
of this volume are therefore referred to page 324 for a tabular 
arrangement of the muscles of the foot and leg, based on the re- 
spective action of each. 

DISTRIBUTION OF THE 4TH LAYER OF THE 
MUSCLES OF THE FOOT. 

The following table illustrates the distribution of the lumbri- 
cales and the interosseii muscles of the foot. 



Toes. 


Lumbricales. 


Dorsal 
Interossei. 


Plantar 

Interosseii. 


2nd. 
3rd. 

4th. 
5th. 


1st. 
2nd. 
3rd. 
4th. 


1st & 2nd, 
3rd. 
4th. 


ISt. 

2nd. 
3rd. 



ACTION OF THE INTEROSSEI MUSCLES OF THE 

FOOT. 

The dorsal interossei of left foot are thus inserted : 



gro. 47"- go. ^o. jst. 



Interossei muscles. ^ ■**■ 




Great toe. 



Phalanges. 



324 MYOLOGY. 

The plantar interossei of the right foot are thus inserted 



1ST. 2 B. QD. 4m. 5V . 



Great toe. 



< «**• Interosseii muscles. 



Phalanges. 

It will thus be seen that the four dorsal interosseii muscles 
abduct from the axis of the 2d toe, while the three plantar inter- 
ossei adduct to the axis of the 2d toe. 

The interossei muscles may therefore be considered, when 
referred to the axis of the 2d toe, to consist of four abductors and 
three adductors, but when referred to the mesial plane of the 
body, the order is reversed and they consist of three abductors 
and four adductors. 



SUMMARY OF THE MUSCLES OF THE CRURAL AND 
PEDAL REGIONS. 

The muscles which act upon the foot maybe thus classified as 
to their function and method of action : 

A Table illustrating both the Action and Point of Origin of the Muscles 
of the Leg and Foot. 



Part acted upon. 



Foot as a whole. 
Toes in common 
Great toe alone 
Second toe alone 
Third toe alone 
Fourth toe alone 
Fifth toe alone . . 



Arising from 
Leo-. 



Arising from 
Foot. 



Total. 



Total No. of 
muscles. 



5 
6 

3 
3 
3 
4 

32 



Total No. of 
tendons, 



7 
7 
7 
7 
7 

42 



MUSCLES OF LEG AND FOOT. 



325 



2 flexors. 



The 8 muscles acting upon the foot as a whole in- ^ 
elude 



Tibialis anticus. 
Peroneus tertius. 
( Gastrocnemius. 
3 extensors. < Soleus. 

( Plantaris. 

1 adductor. •{ Tibialis posticus 

2 abductors. j Peroneus longus. 
( reroneus brevis. 

8 

The soleus and gastroc nemius muscles have a tendon in common, thus causing only \ 
tendons to exist. 

Flexor longus digitorum. 
Extensor longus digitorum. 

{Flexor brevis digitorum. 
Extensor brevis digitorum. 
Accessorius. 



The 5 muscles acting in com 
mon upon the toes include . . , 



2 arising from leg. 



The 6 muscles acting 
big toe alone include. 



on the 



2 from leg. 



j Extensor proprius pollicis. 



The 4 muscles acting upc 



Flexor longus pollicis. 
("Abductor pollicis. 
J Adductor pollicis. 
I Flexor brevis pollicis. 
[ Transversus pedis. 

( Flexor minimi digiti. 

,, j.,, T . , . 1 1 J Adductor minimi digiti. 
the little toe alone include < ~ , . . , & 

One plantar interosseous. 

I One dorsal interosseous. 



4 from foot. 
6 



The SEVEN TENDONS ACTING ON EACH TOE may be thus enum- 
erated : 

f Extensor brevis digitorum. 
I Abductor pollicis. 
1st phalanx, 5 muscles. *| Adductor pollicis. 

j Flexor brevis pollicis. 
(^Transversus pedis. 

1 , , , < Extensor longus pollicis. 

2nd phalanx, j> muscles, j Fkxor longu jf pol Y icis> 



Tendons acting upon the 

GREAT TOE 



Tendons acting upon the 

LITTLE TOE 



f Flexor minimi digiti. 

. . 1 t 1 j Adductor minimi digiti, 

1st phalanx, 4 muscles.^ „ , , . . , & ' 

r ' ^ j 3rd plantar interosseous. 

l^4th lumbricales. 
2nd phalanx, I muscle. •{ Flexor brevis digitorum. 

srd rmalanx 2 muscles \ Extensor lon § us digitorum. 
L 3rd phalanx, 2 muscles, i Fkxor j g digitorum . 



Tendons acting 
OTHER TOES.. 



upon the 



1st phalanx, 3 muscles. 



Two interossei. 
Lumbricales. 

Flexor brevis digitorum. 
Extensor brevis digitorum. 



■i 2nd phalanx, 2 muscles 

\ , , , , ( Flexor longus digitor 
l3vd phalanx, 2 muscles, i ^„.„„._„ 1* %:~u 



\ Extensor longus digitorum. 



326 



MYOLOGY. 



Appended to this chapter will be found a classified table illus- 
trative of the distribution of the motor nerves of the muscles of 
the lower extremity ; and also a diagramatic table to assist the 
student in computing the number of the muscles divided in the 
various amputations through the hip, knee and ankle joints. 



MUSCLES OF LOWER EXTREMLTY. 



327 



GENERAL ACTION OF THE MUSCLES OF THE 
LOWER EXTREMITY. 

The flexor and extensor muscles are arranged alternately on 
opposite sides of the limbs. Hence it follows that when a muscle 
of the lower extremity passes over any two of the four principal 
joints, it flexes the one and extends the other or vice versa. 

To the above rule there are only two exceptions. 

1st. The sartorius muscle, which produces flexion of two joints. 

2d. The gracilis muscle, which flexes the knee and adducts the 
limb, when it is extended. 

The motions of the four principal joints of the lower extrem- 
ity are thus named : 



Nomenclature of the Motions of the Lower 
Extremity. 


Joints. 


If moved 
forwards. 


If moved 
backwards. 


Hip. 

Knee. 

Ankle. 

Metatarso-phalangal. 


Flexion. 
Extension. 
Flexion. 
Extension. 


Extension. 
Flexion.,, 
Extension. 
Flexion. 



PRINCIPLES OF LEVERAGE AS EXHIBITED IN 
THE FOOT. 

The three different forms of levers are beautifully represented 
in the foot. 

The first order of levers, viz., where the fulcrum is in the 
centre, is exhibited by tapping the floor with the toes. 

Muscles. 



Toes. 



In this case, the ankle becomes the fulcrum (F), the muscles 
attached to the heel the power (P), the foot the resistance (R), to 
be overcome. 

The second order of levers where the resistance to be overcome 



323 



MYOLOGY. 



is in the middle,is represented, in the foot, when an effort to stand 
upon the toes is made. 



Muscles. 



Weight of 
body. 



Heel. 



Toes. 



In this case, the toes become the fulcrum (F), the weight of 
the body the resistance to be overcome (R), and the power (P) re- 
mains at the heel. 

The third order of levers, where the power is applied in the 
middle, is represented in the foot when a weight is raised, when 
situated upon the toes. 

Muscles. 



Heel. 



ZW 



■* Toes. 



In this case, the heel or the ankle-joint become the fulcrum (F), 
the muscles of the anterior crural region the power (P), and the 
weight upon the toes the resistance to be overcome. 

To recapitulate then, we have three orders of levers named 
respectively the 1st, 2nd and 3rd. These orders may be thus 
represented : 



Lever of 1st order. — 



Lever of 2nd order. fL 



The centre being the ful- 
crum. 



-1 The centre being the re- 
sistance. 



Lever of 3rd order. 2- 



_£ The centre being the 



*■* power. 

A single rule can be given to remember these orders, since the 
centres F. R. P. rhyme with the number of the orders 1, 2, 3. 

In the foot these principles of leverage have great anatomical 
importance. 

The first order promotes the equilibrium of the body. 
The second order tends to overcome resistances. 
The third order facilitates motion. 



MUSCLES OF LOWER EXTREMITY. 



329 



The following table indicates the number of muscles divided 
in amputation either at the hip, knee or ankle joints : 

A Table Illustrating the Muscles Divided in Amputa- 
tions THROUGH THE PRINCIPAL JOINTS OF THE LOWER 

Extremity. 



Muscles passing over 

two joints. 



Muscles passing over 
one joint. 



TRUNK' 



Sartorius. 

Rectus femoris. 

Gracilis. 

Biceps. 

Semi-tendinosus. 

Semi-membranosus 



Gastroc nemius. 
Plantaris. 




Total 8 



T Psoas magnus. 

Iliacus. 

Tensor vaginae femoris. 

Pectineus. 

Adductor longus. 

Adductor brevis. 

Adductor magnus. 

Gluteus maximus. 

Gluteus medius. 

Gluteus minimus. 

Pyriformis. 

Gemellus superior. 

Obturator internus. 

Gemellus inferior. 

Obturator externus. 
LQuadratus femoris. 
f Vastus externus. 
J Crureus. 
1 Vastus internus. 
[Popliteus. 



f Tibialis anticus. 
Extensor proprius pol. 
Extensor longus dig. 
Soleus. 

Tibialis posticus. 
Flexor longus pollicis. 
Flexor longus digitorum 
Peroneus longus. 
Peroneus brevis. 
Peroneus tertius. 



This table is constructed for the purpose of enabling the stu- 
dent to ascertain the names and numbers of the muscles divided 
in cases of amputation through the principal joints of the lower 
extremity. The horizontal lines represent the segment of the 
limb. The oblique lines represent the group of muscles passing 
from one segment to another, and opposite which are their names. 

In order to ascertain the number of muscles divided in am- 
putation through any joint, the knife of the surgeon, placed be- 
tween the various segments, necessarily intersects two or more 
oblique lines. Add up the respective number at the lower end 
of each one of these lines, and the sum will indicate the number of 
muscles divided. 

A more detailed explanation of this table, however, will be 
found appended to a similarly arranged table under the chapter 
upon the muscles of the upper extremity on page 298 of this work. 



330 



MYOLOGY. 



Table Illustrating the Principal Muscles Involved in 
the Different Varieties of Talipes. 

Name of Muscle. Form of Talipes. 

Gastrocnemius ^~——^^ Talipes equinus. 

Soleus 

Plantaris. 

Tibialis anticus ._ t, ,. 

^^^~~ ' _i — — I alipes varus. 

Tibialis posticus ■ — >~««^^^ 

Peroneus longus -^^^^ "^^>Talipes calcaneus. 

Peroneus brevis - ""~*^ ><;: ^-' 

Peroneus tertius ^~^~~ ~ ^ == ===^ Talipes valgus# 






EXTREMITY. 



NERVJ 



Lumbar Plexi 
i. Ant. Cru 



Psoas Magnus, and Psoas Parvus. 



llliacus, Sartorius, Rectus Femoris, Vastus Externus, 
Vastus Internus, Crureus, and Subcrureus. 




Names of the Muscles. 



2. Obturator ^ rac ^ s ' 3 Adductors, Pectineus, and Obturator Ex- 
ternus. 



Pyriformis, Gemellus Superior, Obturator Internus, 
Gemellus Inferior, and Quadratus Femoris. 

ensor Vaginae Femoris, Gluteus Medius and Minimus. 

Sci|Gluteus Maximus. 

Semitendinosus, Semimembranosus 

PopliPopliteus, Gastrocnemius, Soleus and Plantaris. 



SciBiceps 



p 0s t ei Flexor Longus Pollicis, Flexor Longus Digitorum, and 
Tibialis Posticus. 

a In|Abductor Pollicis, Flexor Brevis Digitorum, Flexor 
Brevis Pollicis, 1st and 2d Lumbricales. 

H' ^ J Abductor Minimi Digiti, Flexor Accessorius, Adductor 
Pollicis, 3d and 4th Lumbricales, Flexor Brevis 
Minimi Digiti, Transversus Pedis, and the 7 In- 
terossei. 



b. Peron 



Ant 



Mu: 

net 



N. B.— The Pel 
the Sacral 
The n 
trunks or 



Tibialis Anticus, Extensor Proprius Pollicis, Extensor 
Longus Digitorum, Peroneus Tertius, and Ex- 
tensor Brevis Digitorum. 



Peroneus Longus, and Peroneus Brevis. 



om the Sciatic Nerve ; and the Gluteus Maxinuts one from 
y.and the remaining forty-five by the Sacral Plexus. 
ited without underscoring are either subdivisions ot main 



MOTOR NERVES OF THE MUSCLES OF THE LOWER EXTREMITY. 



Ant. Crural ... 
Obturator ... 

Super. Gluteal 
Small Sciatic 
Great Sciatic 
<i. Popliteal ... 

Peter Pibial 

a. Int. Plantar 
8. Extern. Plant; 



i. Peroneal ... 

Anter. Tibial 



Psoas Magnus, and Psoas Pi 



Vastus Externus, 
astus Internus, Crureus, and Subcrureus. 

Gracilis, 3 Adductors, Pectineus, and Obturator Ex- 



liacus, Sartorius, Rectus Femoris 
Vastus Internus, Crureus, and 



Pyriformis, Gemellus Superior, Obturator Internus, 
Gemellus Inferior, and Quadratus Femoris. 

Tensor Vagina: Femoris, Gluteus Medius and Minimus. 

Gluteus Maximus. 



Biceps Semitendinosus, Semimembr 

Popliteus, Gastrocnemius, Soleus and Plantaris. 

Flexor Longus Pollicis, Flexor Longus Digitorum, and 
Tibialis Posticus. 

Abductor Pollicis, Flexor Brevis Digitorum, Flexor 
Brevis Pollicis, 1st and 2d Lumbricales. 

Abductor Minimi Digiti, Flexor Accessorius, Adductor 
Pollicis, 3d and 4th Lumbricales, Flexor Brevis 
Minimi Digiti, Transversus Pedis, and the 7 In- 



Tibialis Anticus, Extensor Proprius Pollicis, Extensor 
Longus Digitorum, Peroneus Tertius, and Ex- 



Longus 



nd Peroneus Br 



B.— The Pectineus receives additional filaments from the Anterior Crural and Accessory Obturator Nerves ; the Adductor Magnus one from the Sciatic Nerve ; and the Gluteus Maximus one from 
the Sacral Plexus. It thus appears, that of the sixty muscles of the Lower Extremity, fifteen are supplied by the Lumbar plex Jr.and the remaining forty-five by the Sacral Plexus. 

The nerves underscored in red are the main nerve trunks derived from the Lumbar and Sacral plexus, while the nerves printed without underscoring are either subdivisions of main 
•ranks or those whose muscular branches are comparatively unimportant. 



ANGIOLOGY. 



THE ARTERIAL SYSTEM. 

The vessels which convey the blood from the heart to the 
systemic capillaries are cylindrical tubes gradually decreasing in 
size as they recede from the central organ. To them the name 
of arteries was given, before the circulation of blood was discov- 
ered or their function suspected, from the belief that they con- 
tained atmospheric air, and it was not until the time of Galen 
that this doctrine was refuted. It was he who first directed 
attention to the fact, that, while in the dead body the vessels 
were for the most part empty, still, in the living body, they con- 
tained the blood. 

The distribution of the arterial system is compared by a 
prominent author to a highly ramified tree, whose main trunk 
consists of the aorta, and whose ramifications extend in all direc- 
tions towards the periphery of the body and the organs con- 
tained within its numerous cavities. So extensive are these ram- 
ifications that but few of the essential parts of our structure es- 
cape their presence, among which, however, may be mentioned the 
hairs, the nails, the epidermis, cartilage and the cornea of the eye. 
Nature has considerably protected this important part of her 
organism from injury, by concealing the larger trunks by invest- 
ing muscles and by placing them on that aspect of the limbs, the 
flexor side as a rule, which is least liable to be exposed to vio- 
lence or to injury. She has moreover encased the main trunk 
of the arterial tree within two cavities, protected largely by bony 
walls, and, where not completely so protected, has covered it 
with soft and elastic viscera and afforded it shelter by the close 
proximity of the vertebral column. 

The branches of arteries vary greatly in their mode of origin 
and in the angle at which they leave the parent trunk. 

We occasionally find a short vessel suddenly dividing into 
numerous branches at the same point, as is the case in the cceliac 
and thyroid axes ; again an artery will send off shoots along its 
entire length and still preserve its identity as the more important 
trunk, as is evidenced in the external carotids, the axillary, the 
brachial, the radial, the ulnar, and the arteries of the lower ex- 
tremity. We find in the third place frequent dichotomous divi- 
sions of large arteries to which the term bifurcation is applied, as 
for example, the division of the abdominal aorta into its two 
terminal branches, the common iliacs ; and the common carotid 
into its terminal branches, the external and the internal carotid 
arteries. 



334 ANGIOLOGY. 

As regards the angle of separation of arterial branches from 
the main trunk we find an equal diversity. Some form an obtuse 
angle, some a right angle, and a few an acute angle with the trunk 
from which they spring. 

It is to be remembered, however, that, while these arterial 
branches are always individually smaller in size than the vessels 
from which they spring, that the area of the supplying trunk 
never equals the combined area of its branches. Authors of 
works upon anatomy frequently compare the arterial system to a 
cone, whose apex only resembles the area of the aorta and whose 
enormous base corresponds to the combined areas of the capilla- 
ries which owe their circulation to its original contents. 

The smaller arteries, in course of their distribution to the va- 
rious parts of the body, communicate freely with each other in 
almost all portions of the body by what is termed anastomosis or 
inosculation ; but, where such a communication occurs between 
vessels of larger calibre, great necessity is perceived to exist for 
unimpaired freedom and activity of circulation. Thus we find 
this condition prominent in the brain, especially at the circle of 
Willis, and also in the mesentery, where vessels of large size com- 
municate ; since, in these situations, circumstances tending to im- 
pede the circulation in any one trunk might otherwise be attended 
with consequences of the gravest import. This condition is also 
perceived in the circulation of the hand and foot. 

Three axioms may be here stated as regards the communica- 
tion of arteries, which deserve attention and which may assist 
memory. 

A. Every artery anastomoses with its fellow, excepting in the 
extremities and a few vessels distributed to viscera. 

As interesting examples of this fact, may be mentioned the 
anastomoses between the two anterior cerebral arteries, by the an- 
terior communicating branch ; between the two obturators, by a 
transverse branch ; between the vertebral arteries, by their union 
to form the basilar ; between the epigastric arteries, by a trans- 
verse branch ; between the two external carotids, by the union of 
nearly all of their branches ; and between the intercostals and the 
upper lumbar arteries of each side, by encircling the trunk. 

The second general axiom is as follows : 

B. Every artery anastomoses with the vessel immediately above 
and below it. 

As marked examples of this fact, we find, in the lower limb, 
the branches of the external iliac artery and those of the femoral 
artery forming a great posterior and a minor anterior anastomo- 



THE ARTERIES IN GENERAL. 



335 



sis ; each of which is sufficient to carry on the entire circulation 
of the limb when required to do so. 

By this arrangement of vessels, in the upper extremity, a chain 
of anastomoses may be traced along the margins of the scapula 
and the inner edge of the arm, till the circulation of the forearm 
and palmar arches is reached. 

From the angle of the eye, the blood can thus flow succes- 
sively through arterial anastomoses along the nose, mouth, cheeks, 
neck, and, by means of the internal mammary and deep epigastric 
arteries, along the entire chest and abdomen, till it reaches the 
vessels of the lower extremity. 

A similar chain of anastomotic channels can be traced from the 
pharynx, along the oesophagus, stomach and intestines, till the 
rectum be reached. 

The vessels of the brain and spinal cord, in a similar way, can 
be communicated with, throughout the length of the spinal cord, 
by means of small vessels, which hold numerous anastomoses with 
the intervertebral, intercostal, lumbar and sacral arteries. 

The third axiom is that : 

C. Every artery anastomoses with itself, by means of its 
branches. 

As interesting examples of this, may be mentioned the 
branches of the external carotids, which anastomose in the neck ; 
and those of the internal carotids, which communicate in the 
brain. 

The branches of the cceliac axis around the stomach, the cor- 
onary arteries within the heart, and the ciliary arteries around the 
iris, also illustrate this rule. While the articular arteries, espe- 
cially those of the knee ; the branches of the obturator artery, 
around the foramen of that name, and the anastomoses of the 
vessels supplying the sphincter muscles of the body, are further 
proofs how thoroughly nature has protected the tissues from any- 
thing tending to produce impaired arterial supply. 

It is due however to the general capillary circulation through- 
out the body, that nature so readily endures the privation of 
blood, dependent upon ligature of main trunks ; since, by them, 
a so-called collateral circulation is rapidly accomplished, the cap- 
illaries undergoing a process of dilatation and thus greatly in- 
creasing their carrying capacity. 

There is one more general statement in reference to the ar- 
rangement of the arterial system to which attention should be 
directed previous to entering into regional anatomy, and that is 
the direction of the vessels in the various regions of the body. 



336 ANGIOLOGY. 

The large arteries, as a rule, pursue nearly a straight course 
but this like all rules has its exceptions. Frequently, however 
the configuration of certain parts demands tortuosity of vessels 
even of large calibre. This we see exemplified prominently in 
the facial artery, which, in the region of the lips and mouth, is 
extremely tortuous as are also its labial branches ; since the in- 
cessant movements of the parts would be restricted, were the 
supplying vessels distributed in a line of direct transit to the parts 
destined to be supplied by them. 

In the uterus also we find the arterial vessels extremely tortu- 
ous. This has been explained on the ground that, during uterine 
expansion, the arteries were thus enabled to bear with ease a 
strain that might otherwise be dangerous to the nutrition of the 
organ if not even to the arterial coats themselves. 

Finally the internal carotids and the vertebral arteries, al- 
though running a course nearly if not absolutely straight, until 
near their entrance to the skull, suddenly become bent into a 
series of short and abrupt curves, as an evident attempt of nature 
to reduce the velocity of the blood current in the cerebral capil- 
laries, by the friction produced by the constantly deviating 
channel through which it is forced to pass. 

STRUCTURE OF ARTERIES. 

The arteries are composed of three coa.ts ; an internal serous 
or epithelial coat, a middle or elastic coat, and an external or 
cellular coat. To the first, the name of tunica intima, and to the 
last, the term tunica adventitia, has been applied by Kolliker, to 
whose investigations much of our present knowledge on this sub- 
ject is due. 

The two inner coats are easily detached from the external coat, 
and, from their inherent elasticity, they even tend to separate 
spontaneously when a ligature is applied to a vessel with a suf- 
ficient degree of pressure to divide them without injury to the 
external coat. The internal coat, however, is more adherent to 
the middle coat, since maceration is required to produce a sepa- 
ration. 

When the artery is fully distended the internal coat is smooth 
and offers little opportunity for friction to the blood current, but 
when the vessel is empty, as after death, this coat is thrown into 
longitudinal and transverse folds. 

The middle coat of the arteries is distinguished from the in- 
ternal coat by the circular arrangement of its fibres, in contradis- 



STRUCTURE OF THE ARTERIES. 



337 



tinction to the elastic fibres of the inner coat, which are arranged 
in a line parallel with the axis of the vessel. In the largest arter- 
ies, this coat is very thick, yellow in color, and highly elastic, 
but as the vessels decrease in size it becomes thinner and is 
finally lost when the arteries approach the capillaries. 

The external coat consists mainly of connective tissue. It is 
thin in the largest arteries, but becomes as thick and often thicker 
than the middle coat, in arteries of small calibre. It consists of 
two layers, an external layer of connective tissue and an internal 
layer of elastic fibres, until the vessels decrease to a medium 
calibre, when the internal elastic coat becomes lost ; the external 
coat, however, remains and gradually becomes thinner as the 
capillary vessels are approached. 

The arterial coats, taken as a whole, are extremely thin, in 
proportion to the size of the vessel, in certain special localities, 
among which may be especially mentioned the cavities of the 
cranium and of the spinal canal. The arteries of the body are 
enveloped, as a rule, in a fibro-areolar investment, termed their 
sheaths. In the extremities, this sheath is usually continuous with 
the deep fascia; but, in the thigh, at its upper portion, it is 
formed by the iliac fascia of the pelvis and the transversalis 
fascia of the abdomen, and, in the neck, by a prolongation of the 
deep cervical fascia. This sheath is loosely connected to the ex- 
ternal coat of the artery by areolar tissue and in many cases it 
affords protection to nerves and veins accompanying the artery. 

The external coat of the larger arteries is supplied with blood- 
vessels, like the organs of the body. These nutrient arteries are 
called vasa-vasorum. They arise either as branches of the artery 
which they supply, or from a neighboring vessel, at a point dis- 
tant to their seat of distribution. Minute veins accompany these 
arteries and return their blood, by means of the venae comites, 
which lie in close connection with the artery. 

Arteries are also supplied with nerves, which are chiefly de- 
rived from the sympathetic system but also partly from the cere- 
brospinal nerves. 

Upon the large arterial trunks these nerves form intricate 
plexuses, while, to the smaller arteries, single nerve filaments are 
distributed. 

The method of termination of the nerve filaments is still a 
matter of doubt. 



338 ANGIOLOGY. 



THE AORTA. 

The aorta, the main trunk of the arterial system, arises at the 
upper portion of the left ventricle, at a point corresponding with 
the inferior surface of the semilunar valves and located on the 
external aspect of the chest, at the left edge of the sternum, be- 
tween the costo-stemal articulations of the third and fourth ribs. 
This point of origin corresponds, posteriorly, to the sixth dorsal 
vertebra, when the respiratory act reaches the end of expiration. 

The aorta may be divided into two distinct portions, viz., the 
THORACIC PORTION, and the ABDOMINAL PORTION. 

The thoracic portion of the aorta may be subdivided into a 
curved portion called the ARCH OF THE AORTA and a dorsal por- 
tion to which the name THORACIC AORTA is usually applied in 
contradistinction to the arch, although the name is, in reality, a 
misnomer unless the arch itself be included. 

The first portion, or the ARCH OF THE AORTA, consists of 
three divisions or segments, called the ascending, transverse and 
descending portions of the arch. 

These segments, at their points of junction, reveal different 
degrees of curvature, giving to the arch, as a whole, an inter- 
rupted and not a continuous curve. 

The ASCENDING PORTION of the arch commences at the infe- 
rior surface of the semilunar valves and passes upwards, at an 
angle towards the right side of the body, for a distance which 
varies from two to three inches. It becomes continuous, at its 
termination, with the transverse portion, at a point correspond- 
ing, externally, with the right side of the sternum, &t its junction 
zvith the second rib. 

The direction of the first portion of the aorta is such that a 
continuation of the axis of the left ventricle, when that organ is 
in repose, impinges upon the convex surface of the aorta at a 
spot nearly corresponding to the point of junction between the 
ascending and transverse portions of the arch, but this point must 
vary somewhat, during life, with the rotary movement of the 
heart. Here is situated a bulging of the aorta, in health, called 
the sinus magnum, and it is here that we first detect disease in the 
form of atheromatous degeneration and aneurismal dilatations. 
This fact seems certainly to accord with the approximate an- 
atomical accuracy of this statement of the direction of the 
ventricular axis, since the current of blood, being thrown with 
the greatest force in the direct axis of the ventricle would, of 



THE AORTA, 



339 



necessity, create upon this local point the greatest friction and 
degenerative changes would therefore be first manifested at this 
situation. 

The first portion of the aortic arch presents for examination 
the following points of interest: 
(i) The coronary arteries. 

(2) The sinuses of Valsalva. 

(3) A constriction at the bases of the aortic valves. 

1. The coronary arteries are two in number, the right and the 
left. The right coronary artery arises from that sinus of Valsalva, 
in which the anterior segment of the aortic valve is lodged 
during the contraction of the ventricle ; while the coronary artery 
of the left side arises from that sinus which lodges the left poste- 
rior segment. They will be described in detail in subsequent 
pages. 

2. The sinuses of Valsalva are depressions in the walls of the 
aorta for the reception of the aortic valves. By their size and depth, 
they cause an increased circumferential measurement of the aorta, 
at a point corresponding to their situation. Thus the average 
circumference of the aorta over the sinuses of Valsalva, may be 
stated as about four inches, while immediately above them the 
circumference falls to three and a quarter or three and a half 
inches. At the situation of the sinus magnum, the aorta, how- 
ever, again expands to a circumference in excess of even the 
neighborhood of the sinuses of Valsalva. 

3. The first portion of the aortic arch presents, finally, a con- 
striction at the bases of the aortic valves, due to on excess of white 
fibrous tissue over the elastic tissue of the aorta and which is 
probably destined as a source of protection to the aortic orifice 
against dilatation or rupture. 

The ascending portion of the arch of the aorta is partly in- 
vested by the pericardium, which is prolonged upon its coats 
for a distance of nearly two inches. 

The relation which this portion of the aorta bears to sur- 
rounding structures may be seen by reference to the following 
table. 



340 



ANGIOLOGY. 



PLAN OF THE RELATIONS OF THE ASCENDING PORTION OF THE 
ARCH OF THE AORTA. 

In front. 
Pulmonary artery. 
Right auricular appendix. 
Peircardium. 
Remains of thymus gland. 



Right side. 
Superior vena cava. 
Right auricle. 




Left side. 
Pulmonary artery. 



Behind. 

Right pulmonary vessels. 
Root of right lung. 

The transverse PORTION of the arch of the aorta begins at 
a point corresponding to the costo-sternal articulation of the sec- 
ond rib of 'the right side and terminates at a point corresponding 
to the superior border of the ^d dorsal vertebra. Its direction 
in the thorax is oblique, since it passes from before backwards 
and from the right towards the left side. From its upper or 
convex border, arise three important arterial trunks, viz., the 
arteria innominata, left carotid and left subclavian arteries. It 
varies in length from three to four inches. Its upper border is 
usually about an inch below the upper margin of the sternum, 
but it varies in its position somewhat during respiration, although 
less than the ascending portion of the arch. 



PLAN OF THE RELATIONS OF THE TRANSVERSE PORTION OF THE 

ARCH. 

A bove. 
I vein \ Left innominate vein. 

Arteria innominata. 
3 arteries. . \ Left carotid. 

Left subclavian. 



In front. 
Left pleura and lung. 

C Left pneumogastric 
3 Nerves ■] Left phrenic nerve. 



Card 



lac nerves. 




Behind. 
Trachea. 
OZsophagus. 
Thoracic duct. 



2 nerves. 



Deep cardiac plexus. 
Left recurrent laryn- 
geal nerve. 



Below. 
Bifurcation of pulmonary artery. 
Remains of ductus arteriosus. 
Left recurrent laryngeal nerve. 
Left bronchus. 



THE AORTA. 34 1 

The DESCENDING PORTION of the arch of the aorta begins at 
the upper edge of the $d dorsal vertebra and curves downwards 
in a nearly straight course, until it reaches the lower border of the 
left side of the ^th dorsal vertebra where the name thoracic aorta 
is usually applied to it. 

PLAN OF THE RELATIONS OF THE DESCENDING PORTION OF THE 

ARCH. 

In front. 
Pleura. 
Root of the left lung. 



Right side. 


/Arch of Aorta. \ 


Left side. 


GEsophagus. 


Descending J 


Pleura. 


Thoracic duct. 


\ Portion. / 





Behind. 
Left side of body of third dorsal vertebra. 

THE ARCH OF THE AORTA AS A WHOLE. 

The three segments of the arch of the aorta vary in their posi- 
tion within the chest during the act of respiration, since the dia- 
phragm, being attached to the pericardium, and, through that 
membrane, to the coats of the large arterial vessels, tends to de- 
press the aorta during inspiration. This respiratory movement 
of the arch of the aorta is however most marked in the ascending 
portion, much less apparent in the transverse portion, and least 
of all in the descending portion. 

The aorta, as a tube, shows constant variations in its calibre. 
At the aortic orifice it is markedly constricted ; at the sinuses 
of Valsalva, it enlarges to a circumference of four inches ; it then 
becomes again constricted, immediately above the sinuses, to a 
circumference of about three and a quarter to three and a half 
inches ; at the junction of the ascending and transverse portions, 
the enlargement known as the sinus magnum gives to the aorta 
a circumference exceeding even that of the region over the sinu- 
ses of the Valsalva ; the transverse portion has a nearly uniform 
calibre of about three and a half inches ; and finally a rapid de- 
crease in size is again present in the descending portion of the 
arch. 

It has already been stated that the axis of the left ventricle 
in repose, if prolonged into the aorta, impinged upon the right 
wall of that vessel, at the point of junction of the ascending and 



342 ANGIOLOGY. 

transverse portions of the arch. It is a matter of surgical inter- 
est that, at this point, is thoracic aneurism most frequently de- 
veloped and atheromanous changes most frequently detected, 
and the explanation of this fact seems to be justly an anatomical 
one. The situation of the innominate artery being just above 
this weak point, and so placed that the current of blood by im- 
pinging upon the roof of the arch shall subject it to a strain 
second only to that borne at the sinus magnum, will also explain 
why this vessel is the next most frequently affected either with 
atheromatous degeneration or aneurism. The left carotid, from 
its anatomical situation, is still less frequently involved than the 
innominate, as it is subjected to less strain ; while the left sub- 
clavian artery, from its situation and the angle at which it leaves 
the arch (nearly ninety degrees), is so ensured against excessive 
pressure that it is rarely the seat of aneurismal dilitations. 

The ascending portion of the arch, being enclosed within the 
pericardium and being also the most frequently affected with 
aneurismal disease of any vessel in the arterial system, presents 
symptoms not in common with aneurismal sacs in other locali- 
ties and which allow of an explanation on a purely anatomical 
basis. 

If the aneurismal sac be situated low down, in the region of 
the aortic sinuses, the right coronary sinus of the heart becomes 
pressed upon early, from enlargement of the tumor in the ante- 
rior direction, since the regurgitation of blood produces the 
greatest pressure upon that aspect of the vessel, and the nutrition 
of the heart may thus be interfered with. In the more advanced 
stages of development, however, the tumor may by pressure im- 
pede either the current in the pulmonary artery, or in the supe- 
rior vena cava ; or it may possibly interfere with the free action of 
the right auricle or even of the right ventricle. Thus cyanosis, 
distended jugulars, a bruit in the pulmonary artery on ausculta- 
tion, or irregular hearts action may ensue. 

If the aneurism of the ascending arch be higher up, as is most 
common, the tumor develops, as a rule, to the right of the 
median line, and, when of large size, tends to approach the ante- 
rior aspect of the thorax. We frequently therefore find the ster- 
num and the ribs of the right side undergoing rapid absorption 
and a pulsating tumor develops in the locality of the manubrium. 
By pressure of the tumor upon the neighboring parts, symptoms 
referred to the right lung and those to impairment of the 
trachea, main bronchi or oesophagus, may also simultaneously 
develop. 



THE AORTA AS A WHOLE. 343 

Aneurism of the transverse portion of the arch of the aorta 
most frequently develops on its right extremity and the poste- 
rior aspect of the vessel. At this point many important rela- 
tions exist, which render the development of a tumor an inevita- 
ble associate of symptoms referred to other localities. 

The trachea, oesophagus and thoracic duct lie in the closest 
relation posteriorly ; the recurrent laryngeal nerve winds around 
the aorta on the left side ; and the large arterial trunks given off 
from its convex or upper border furnish the blood supply to the 
head and the upper extremities. 

Thus the pressure of an aneurismal tumor in this locality, by 
affecting the bronchi or the trachea, may produce dyspnoea 
cough, haemoptysis and stridulous respiration ; by affecting the 
oesophagus, deglutition may be impaired or destroyed ; by creat- 
ing pressure on the thoracic duct, the patient may die of inanition. 

Pressure upon the recurrent laryngeal nerve has often pro- 
duced symptoms so analogous to those of inflammation of the 
larynx, that tracheotomy has often been performed from an 
error in diagnosis. 

By an obstruction of the innominate artery, either partial or 
complete, the radial pulse of the right side may be either dimin- 
ished in its volume or entirely absent. 

By pressure upon the innominate veins, the venous return 
from the head and upper extremities may be impaired and thus 
cyanosis, oedema, and diminished temperature, of the parts, in 
which the circulation is obstructed, may result. When an aneu- 
rismal dilatation of the aorta develops to a great size in an upward 
direction, it may simulate aneurism of the arteria innominata, by 
appearing above and to the right of the sternum ; and, by reaching 
the brachial plexus of nerves in the neck, it may produce shoot- 
ing pains running down the upper extremity to the tips of the 
fingers. 

Aneurism of the descending portion of the arch of the aorta 
is usually situated upon the left side of the vessel and develops 
in a backward direction. By pressure, it most frequently causes 
absorption of the adjoining ribs and bodies of the vertebrae. It 
may, however, produce also symptoms referable to pressure upon 
the trachea, left bronchus, oesophagus and of the right or left 
lung. In case of spontaneous rupture of the sac, the blood may 
be poured out into the pleural cavity (usually that of the left 
side) ; or in rare cases, into the trachea, left bronchus, oesophagus, 
or into the substance of the left lung. In this variety ot aneurism. 
an intercostal neuralgia of a severe and constant type, is produced 



344 ANGIOLOGY. 

by pressure of the growing tumor upon those intercostal nerves 
which lie between it and the bony ribs. 



A TABLE OF THE BRANCHES OF THE ARCH OF 

THE AORTA. 

i. f RIGHT CORONARY. 

LEFT CORONARY. 

f Right exter. 
f Right common J nal carotid 

INNOMINATE J CAR0TID • • 



ARCH OF THE AORTA 

(5 branches.) 



l nal carotid 

Right subclavian. 

f Left external 

LEFT COMMON CAROTID.... J T CAROTID - 

) Left internal 

l carotid. 

I LEFT SUBCLAVIAN. 

The following table of the branches of the arch of the aorta 
shows that five principal arterial trunks are given off, viz., the two 
coronary, the arteria innominata, the left common carotid and 
the left subclavian arteries. 

CORONARY ARTERIES. 

The two coronary arteries arise from the aorta close to its 
point of origin. 

The right coronary artery is largest in its size and arises from 
that sinus of Valsalva which lodges the anterior segment of the 
aortic valve ; while the left coronary artery arises from that sinus 
of Valsalva which lodges the left posterior segment of the aortic 
valve. These two vessels form an arterial circle around the base 
of the heart, being lodged within the auriculo-ventricular grooves ; 
and they also anastomose, at the apex of the heart, through 
branches which run in the groove between the ventricles. 

The coronary arteries receive their blood supply during the 
diastole of the heart, the blood being forced into them partly by 
gravity, and partly by the elastic recoil of the aorta ; although the 
circulation of these vessels is furthermore assisted by the relaxed 
condition of the heart walls. They supply the heart substance 
with nutrition, and empty their blood, through the coronary veins, 
into the right auricle of the heart. 



BRANCHES OF AORTIC ARCH. 



ARTERIA INNOMINATA. 



345 



This artery arises from the transverse arch of the aorta at an 
average distance of three and a half inches from the aortic valve. 
It is separated by an interval of less than one half of an inch from 
its adjoining branch, viz., the left common carotid artery. 

In calibre it exceeds or equals the combined areas of the four 
remaining branches of the arch of the aorta. Its average length 
is about one inch and a half. 

The arteria innominata terminates at the right sterno-clavicu- 
lar articulation, behind and between the two points of origin of 
the sterno-mastoid muscle. At this point, it bifurcates into the 
right common carotid and the right subclavian arteries, the former 
arising from the anterior portion of the arteria innominata, while 
the latter forms a direct continuation of the curve of that vessel. 

The course of the arteria innominata corresponds to a line 
drawn from the middle of the sternum, at the point of junction 
of the manibrium and the gladiolus, to the right ster no-clavicular 
articulation. 

PLAN OF THE RELATIONS OF THE ARTERIA INNOMINATA. 

In front. 

n-, •, ( Sterno-thyroid. 

Two muscles. ■{ c , , J ., 

( Sterno-hyoid. 

Remains of thymus gland. 

,-p ■ \ Left vena innominata. 

1 wo veins. . . \ n • , . • { . ., . , 

i Right inferior thyroid. 

Inferior cervical cardiac branch of right 
pneumogastric nerve. 



Right side. / \ Leftside. 

Right vena innominata. /Arteria Innom-\ Remains of thymus gland, 

Right pneumogastric nerve. I inata. I Left carotid artery. 

Pleura. 



Behind. 
Trachea. 

The inferior thyroid veins cross the artery low doivn near its 
seat of origin. 

The muscles, designated in the table of relations, separate the 
upper portion of the artery from the sternum, while the thymus 
gland and the innominate vein separate its middle portion from 
the sternum. 




346 angiology. 

Collateral Circulation. 

The arteria innominata, if tied, no longer furnishes blood to 
the right side of the head or to the right upper extremity. Cer- 
tain indirect channels are therefore forced to carry an additional 
amount of blood to supply these parts with proper nutrition. 

The various points of collateral circulation, which are found 
to exist when a subject is injected, whose arteria innominata has 
previously been ligated, are as follows. 

1. A regurgitant current through the circle of Willis, by means 

of the left carotid and vertebral arteries, which fills the 
vessels of the right side immediately after the applica- 
tion of the ligature. 

2. The carotids of both sides anastomose, by means of their 

branches which meet in the median line. These 
branches are as follows : 

The superior thyroid arteries. 

The lingual arteries. 

The facial arteries. 

The internal maxillary arteries. 

The occipital arteries. 

The temporal arteries. 

3. The subclavian artery derives blood directly from the 

anastomosis of the following vessels. 

Superior intercostal with first aortic intercostal. 

Profunda cervicis with princeps 'cervicis. 

Lower intercostals with internal mammary branches. 

Lower intercostals with axillary branches. 

Lnternal mammary with deep epigastric artery. 

The two inferior thyroid arteries .with each other. 

COMMON CAROTID ARTERIES. 

The two common carotid arteries differ in their points of ori- 
gin upon the right and the left side of the neck. 

The right common carotid arises, as one of the branches of 
bifurcation of the arteria innominata, behind the right sterno- 
clavicular articulation ; while the left common carotid arises from 
the highest part of the aorta, and has therefore a thoracic and 
a cervical portion. 

The thoracic portion of the left common carotid artery is 
deeply situated and terminates at the root of the neck. 



COMMON CAROTID ARTERIES. 



347 



PLAN OF THE RELATIONS OF THE THORACIC PORTION OF THE 
LEFT COMMON CAROTID ARTERY. 

In front. 
Sternum. 

Sterno-hyoid muscle. 
Sterno-thyroid muscle. 
Thymus gland. 
Left vena innominata. 



Internally. 
Arteria innominata. 




Externally (2 structures). 
Left pneumogastric nerve. 
Left subclavian artery. 



Behind. 
Trachea. 
CEsophagus. 
Thoracic duct. 

Within the neck, the two common carotid arteries resemble 
each other so closely that one description will answer for both. 
They extend from behind the sterno-calvicular articulation of 
either side, in a direction upwards and outwards, to the upper 
border of the thyroid cartilage, where each artery bifurcates into 
the external and internal carotid arteries. 



348 



ANGIOLOGY. 



PLAN OF THE RELATIONS OF THE COMMON CARTOID ARTERY 

IN THE NECK. 

In front. 
Integument. 

Superficial and deep fascia, 
f Platysma. 
j Sterno-mastoid. 
Muscles. \ Sternohyoid. 

| Sternothyroid. 
L Omo-hyoid. 



Veins. -\ 



i Superior thyroid. 
Middle thyroid. 
Anterior jugular. 



Nerves. 



j Inconstant. \ T . ' -. 
^ ( Lingual. 

Descendens noni. 

Communicans noni. 

Sterno-mastoid artery. 



Externally. 
Internal jugular vein. 
Pneumogastric nerve. 




Internally. 
Pharynx. 
Larynx. 
Trachea. 
Thyroid gland. 
Recurrent laryngeal nerve. 
Inferior thyroid artery. 



Behind. 

Cervical vertebrae. 

iRect. cap. ant. major. 
Longus colli. 
Scalenus anticus. 
j Recurrent laryngeal. 
\ Sympathetic. 
Inferior thyroid artery. 



Nerves. 



Within the sheath of this vessel are enclosed the internal jugu- 
lar vein and the pneumogastric nerve. 

The common carotid artery within the neck is, at first, deeply 
situated but becomes superficial, near its point of termination. 
Its direction may be represented, upon the surface of the neck, 
by a line drawn from the sternal end of the clavicle to a point mid- 
way between the angle of the jaw and the mastoid process of the 
temporal bone. 



EXTERNAL CAROTID ARTERY. 349 



EXTERNAL CAROTID ARTERY. 

This artery arises from a point corresponding to the upper 
border of the thyroid cartilage and is directed upwards towards 
an interval which exists between the neck of the condyle of the 
jaw and the external auditory meatus, where it divides into its 
two terminal branches, viz., the temporal and internal maxillary 
arteries. In its course, which is slightly curved upon itself, it 
presents, at its lower portion, a curve, the concavity of which 
looks towards the lobule of the ear ; and, midway, between its 
points of origin and termination, it takes a sharp inclination back- 
wards into the interval where it terminates. The point of bifur- 
cation of the external carotid artery lies on a level with the con- 
dyle of the jaw. In its course through the neck it gives off. eight 
branches of varying sizes, and therefore diminishes rapidly in its 
calibre as it approaches its point of bifurcation. 

In the adult, this artery is of nearly equal size with the inter- 
nal carotid although, in the foetus, it is usually smaller. It is 
more superficially placed near its point of origin than at its point 
of termination. Its average length varies from 2-f to 3^ inches 
although it may occasionally reach a length of four inches or even 
fall short of the normal standard. 

PLAN OF THE RELATION OF THE EXTERNAL CAROTID ARTERY. 

In front. 

Integument. 

Superficial and deep fascia. 

{Platysma. 
Diagastric. 
Stylo-hyoid. 

™" fe" ; 

Hypoglossal nerve. 
Parotid <rland. 



Internally. 
Pharynx. 
Hyoid bone. 
Ramus of lower jaw. 
Parotid gland. 



Behind. 

Nerves. . I Glossopharyngeal. 
t Superior laryngeal. 

Muscles.*. \ Styjo-glossus. 

( atylo-pharyngeus, 
Farotid gland. 




350 



ANGI0L0GY. 



A TABLE OF THE BRANCHES OF THE EXTERNAL 
CAROTID ARTERY. 

fHyoid. 

f Superior thyroid J Sterno-mastoid. 

J Superior laryngeal. 

[Crico-thyroid. 

fHyoid. 

Lingual J P° r f. alis li | 1 § ua - 

1 Sublingual. 



EXTERNAL 
CAROTID 
ARTERY. 4 

(8 branches.) 



[ Ranine. 



r In the neck. 



Facial 



On the /ace. 



Occipital 



Posterior auricular. 



f Inferior palatine, 
j Tonsillar, 
j Submaxillary. 
[ Submental. 
r Muscular. 
Inferior labial. 
Inferior coronary. 
Superior coronary. 
Lateralis nasi. 
Angular, 
f Muscular. 
J Auricular. 
I Inferior meningeal. 
(_ Arteria princeps cervicis. 
Stylo-mastoid. 
Auricular. 
( Muscular branches. 
Ascending pharyngeal. . -j Pharyngeal branches. 
( Meningeal branches. 
Transverse facial. 
Anterior temporal. 
Middle temporal. 
Posterior temporal. 
Anterior auricular. 

f Tympanic, 
' Maxillary por- J Middle meningeal 

tion (4)1 Small meningeal. 

[inferior dental, 
f Deep temporal. 
Pterygoid por- J Pterygoid. 

tion (4) j Masseteric. 

[_ fiuccal. 
f Alveolar, 
j Infra-orbital. 
Posterior palatine. 
Vidian. 

Pterygo-palatine. 
Sphenopalatine, 
(nasal.) 



Temporal. 



I Internal maxillary.. 



Spheno-maxillary j 
portion ... (6) 



In the preceding table are shown the eight branches of the ex- 
ternal carotid artery, in the order in which they are given off, as 
well as the principal branches of each, most of which are named 
either from the direction of their course or from the parts to which 
they are distributed. 

These eight branches arise however from different aspects of 
the external carotid artery as is shown in the following classifi- 
cation. 



BRANCHES OF EX TERN A L CARO TID. 3 5 1 

f Superior thyroid. 

The branches \ From its anterior aspect (4) \ Y^l' 

of the Exter- [ Internal maxillary. 

NAL carotid ^ (Occipital. 

artery aie 1 From itg p osterior aspect (3) \ Posterior auricular. 

given off as ' * ] Temporal, 

follows : V . . , . , / \ 1 a j 1 

I From its posterior and internal aspect.. (I) «( Ascending pharyngeal. 

BRANCHES OF EXTERNAL CAROTID ARTERY. 

Of the eight branches which are given off from the external 
carotid artery, some have no special importance, save their 
branches of distribution, which can be easily acquired from the 
tabular arrangement which has previously been given. It has 
been deemed sufficient therefore to enumerate only those points 
pertaining to the separate vessels or their branches, which pos- 
sess some surgical interest. 

SUPERIOR THYROID ARTERY. 

This artery is fourth, in point of size, of the branches of the 
external carotid. It arises, on the average, about one-eighth of 
an inch from the point of bifurcation of the common carotid. It 
has four branches, three of which are constant. The sterno- 
mastoid branch is often called the descending cervical branch. 

The superior thyroid artery supplies the muscles of the hyoid 
bone, the sterno-mastoid and neighboring muscles, the muscles, 
mucous membrane and glands of the larynx, and the upper and 
outer surface of the thyroid gland. It can often be distinctly felt 
by placing the finger upon the upper and front portion of the thy- 
roid gland. 

The crico-thyroid branch is often wounded in the operation of 
laryngotomy, while the sterno-mastoid branch possesses a surgical 
importance from its relation to the sheath of the common carotid 
artery. The superior laryngeal branch has, in several instances, 
caused fatal hemorrhage in attempts to relieve oedema glottidis 
by puncture. 

LINGUAL ARTERY. 

The lingual artery arises at a point situated about three quar- 
ters of an inch above the point of bifurcation of the common car- 
otid artery, and, in point of size, is third of all the branches of the 
external carotid. In every three and a half cases, this artery, 
however, arises by a common trunk in connection with some other 
vessel. 



352 



ANGIOLOGY. 



The lingual artery lies, at first, in close relation to the greater 
cornu of the hyoid bone, to which its direction is nearly parallel, 
and then suddenly ascends in nearly a perpendicular direction, to 
the under surface of the tongue, where it is again deflected and 
passes in a tortuous course towards the tip of the tongue, under 
the name of the ranine artery. 

It lies in relation with the middle constrictor muscle, in its 
first portion ; but is subsequently crossed by the tendon of the 
digastric muscle and also by the stylo-hyoid and the hyoglossus 
muscles. It is separated from the hypoglossal nerve by the hyo- 
glossus muscle. 

In the mouth, its ranine branch is extremely superficial and its 
pulsation can often be detected by the finger. 

The lingual artery is often divided, near its point of origin, in 
cases of cut-throat or it may be involved in injuries to the mouth 
or in deep ulcerations of the tongue. 

FACIAL ARTERY. 

The facial artery arises most frequently at a distance of about 
one inch from the bifurcation of the common carotid artery. It 
is the largest branch of the external carotid artery and its course 
may be divided, for convenience of description, into a cervical 
portion and a facial portion. 

The cervical portion passes obliquely upwards and forwards, 
beneath the body of the lower jaw, to the submaxillary gland, in 
which it lies imbedded in a groove. 

The facial portion extends upward over the body of the jaw, 
crossing at the anterior inferior angle of the masseter muscle, and 
ascends upwards and forwards across the cheek to the angle of 
the mouth ; it then passes up the side of the nose, and terminates 
at the internal canthus of the eye, under the name of the angular 
artery. 

This artery is remarkable for its tortuosity, and its pulsations 
can easily be detected by the finger at the point where it crosses 
the angle of the body of the jaw. It is accompanied, throughout 
its entire course by the facial vein, which, unlike the artery is 
not tortuous ; but, upon the face, it is separated from it by a con- 
siderable interval. 

It is crossed, in the face, by the branches of the facial nerve ; 
and the infra-orbital nerve lies beneath it. 

The branches of the facial are ten in number, four of which 
are given off in its cervical portion, and the remaining six upon 
the face. 



CCIPI TAL AR TER Y. 



353 



The facial artery, through its numerous branches, anastomoses 
with the following vessels. 

1. The opposite facial, through the branches which reach the 

median line. 

2. The internal maxillary, through four of its branches, viz., 

the infra-orbital, the nasal, the inferior dental, the 
posterior palatine. 

3. The lingual, through its sublingual branch. 

4. The internal carotid, through its ophthalmic branch. 

5. The temporal, through its transverse facial branch. 

6. The ascending pharyngeal, in the pharynx and the soft 

palate. 

By means of the fourth of the anastomoses above mentioned, 
the internal and the external carotid arteries have a free point of 
collateral circulation ; while the second group of anastomoses serves 
also to establish a free communication between the superficial 
and the deep branches of the external carotid artery. 

The facial artery is liable to be the source of serious hemorrh- 
age in wounds of the lip or in operations about the mouth or lips. 

The angular artery (the terminal branch of the facial) has a 
point of practical surgical interest connected with it, from its re- 
lation to the lachrymal sac ; since it passes through it along the 
inner border of the orbit, and, in case of operation for lachrymal 
fistula, the sac should therefore be opened upon its external por- 
tion in order to avoid a wound to this vessel. 

OCCIPITAL ARTERY. 

The occipital artery arises from the posterior part of the ex- 
ternal carotid, nearly opposite to the point of origin of the facial 
artery. Its point of origin corresponds therefore nearly to the 
lower border of the digastric muscle. 

This artery is partially covered, at its point of origin, by the 
parotid gland, and the hypo-glossal nerve winds around it. 

The course of this vessel is long and winding, passing at first 
perpendicularly in front of the transverse processes of the cervical 
vertebrae ; making a sharp turn opposite the atlas ; passing in a 
horizontal direction along the base of the skull to the occiput ; 
and then ramifying beneath the integument. It is in point of 
size, usually the sixth of the eight branches of the external carotid 
artery. 

It crosses, in its course, the internal carotid artery, the internal 
jugular vein, the spinal accessory and pneumogastrie nerves. 



354 ANGIOLOGY. 

The occipital artery may be felt at the middle of a line d? awn 
from the occipital protuberance to the mastoid process of the tem- 
poral bone. 

This artery gives off four branches, as can be seen in the table 
of the branches of the external carotid artery, previously given. 

The arteria princeps cervicis, the large branch of the occipital 
artery, possesses surgical importance, since it affords a source of 
collateral circulation in case of ligature of the common carotid 
artery. 

The relation of the occipital artery to the hypoglossal nerve, 
which winds around it, has been explained as a possible effort on 
the part of nature to protect this nerve from tension during the 
protusion of the tongue; since it is forced to descend for some dis- 
tance before becoming looped around the vessel, and thus is 
afforded great latitude of motion and a proportionate ability to 
endure strain from the elasticity of the artery, which would be 
absent were this nerve wound around a bony prominence. 

POSTERIOR AURICULAR ARTERY. 

This vessel is of small size and arises from the posterior aspect 
of the external carotid artery, in the vicinity of the apex of the 
styloid process of the temporal bone, or at a point about two 
inches from the point of bifurcation of the common carotid artery. 

It is crossed by the facial nerve, in front ; and by the spinal 
accessory nerve, behind, at a point corresponding to the junction 
of the cartilage of the ear and the mastoid process of the tem- 
poral bone. 

The stylo-mastoid branch of this artery bears a close relation 
to the facial nerve, at the stylo-mastoid foramen, where that nerve 
escapes. 

The auricular branches are distributed to the back part of the 
cartilage of the ear. 

The muscular branches are distributed to the stylo-hyoid, the 
sterno-mastoid, and the digastric muscles. 

This artery supplies several branches to the parotid gland. 

The posterior auricular artery can be often felt at the apex of 
the mastoid process of the temporal bone. 

ASCENDING PHARANGEAL ARTERY. 

This artery arises from the posterior part of the external car- 
otid, at a point situated in about three quarters of an inch from 
the point of bifurcation of the common carotid artery. It as- 



TEMPORAL A R TER V. 355 

cends vertically between the internal carotid artery and the lat- 
eral wall of the pharynx, till it reaches the base of the skull. 

This artery gives off three sets of branches of distribution, as 
follows : 

1st, those distributed to muscles and nerves, called the ex- 
ternal set, since they are directed outwards. 
2nd, those distributed to the pharynx, which pass towards the 

median line of the body. 
3rd, those distributed to the meninges of the brain, called the 
vertical set, since they pass upwards to reach the cav- 
ity of the cranium. 
The meningeal branches of this artery enter the cavity of the 
skull through the jugular foramen, the foramen lacerum basis 
cranii and the anterior condyloid foramen. They are distributed 
to the dura mater. 

TEMPORAL ARTERY. 

This artery is the smaller of the two terminal branches of the 
external carotid artery and appears to be its direct continuation 
upon the exterior surface of the skull. It arises slightly below 
the condyle of the lower jaw, in the substance of the parotid 
gland, and does not become superficial for the first inch of its 
course. This artery may be located on the exterior of the skull, 
at a distance of one and a quarter inches behind the external an- 
gular process of the frontal bone. It may be compressed at the 
point where it crosses the zygomatic process of the temporal 
bone. It gives off the following branches : 

Branches to the parotid gland. 

Branches to the masseter muscle. 

Branches to the temporo-maxillary articulation. 

The transverse facial artery. 

The middle temporal artery. 

The anterior auricular artery. 

The anterior temporal artery. 

The posterior temporal artery. 
The transverse facial branch runs forwards parallel with the 
parotid or Steno's duct, and between it and the zygoma. 

There are five temporal arteries in the body, four of which in- 
clude the temporal artery and its three temporal branches, while 
the deep temporal artery is given off from the internal maxillary. 

The temporal artery has been tied to relieve excessive vas- 
cular supply of the orbit, eye, or meninges of the brain. It is sel- 



356 ANGIOLGGY. 

dom used for bleeding, although it is very superficial, since the 
temporal fascia, from its inelasticity, renders subsequent compres- 
sion difficult and also prevents the free escape of blood. 

INTERNAL MAXILLARY ARTERY. 

This artery is the deep terminal branch of the external carotid ; 
which, in size if not in direction, is a continuation of that vessel. 

It pursues a winding course, under cover of the ramus of the 
jaw, from its point of origin, where it is concealed by the parotid 
gland, till it reaches the spheno-maxillary fossa, where it gives off 
its terminal branches. 

This artery is usually divided into three portions for conve- 
nience of description, as follows : 

1. The maxillary portion. 

2. The pterygoid portion. 

3. The spheno-maxillary portion. 

The maxillary portion extends from its point of origin to the 
anterior border of the internal lateral ligament of the lower jaw. 

The pterygoid portion of this vessel is defined by its attach- 
ment to muscles through its muscular branches ; although it is 
named from its relation to the external pterygoid muscle, on which 
it rests. 

The spheno-maxillary portion is contained in the spheno-max- 
illary fossa, which it enters through an interval between the two 
heads of the external pterygoid muscle. At this point the artery 
lies in close relation to Meckel's ganglion. 

The branches of the internal maxillary artery are fourteen in 
number, four of which are given off in the first portion, four in 
the second portion and six in the third portion. The names of 
these branches, in the order in which they are given off, will be 
found in the table of the distribution of the external carotid 
artery and its branches. 

The tympanic branch enters the tympanum through the fis- 
sure of Glaser. 

The middle meningeal branch enters the cranium through the 
foramen spinosum. Its branches are distributed as follows : 

1. Branches to the Gasserian ganglion. 

2. Petrosal branch, which enters the hiatus fallopii and accom- 

panies the facial nerve. 

3. Orbital branches, which anastomose with the vessels of the 

orbit. 

4. Temporal branches, which perforate the temporal bone and 

• join the deep temporal artery, in the temporal fossa. 



INTERNAL CAROTID ARTERY. 357 

The situation of the middle meningeal artery corresponds to 
a point on the exterior surface of the skull situated one inch 
and a half behind, and one half inch above the external angular 
process of the frontal bone. 

The small meningeal branch enters the cranium through the 
foramen ovale. 

The inferior dental branch enters the inferior dental canal and 
is accompanied by a nerve of the same name. 

The four branches given off in the pterygoid portion of the ves- 
sel are distributed to the muscles of mastication. 

The alveolar branch, supplies the gums, some teeth in the 
upper jaw, and the antrum. 

The infra-orbital branch, accompanies the superior maxillary 
nerve, in its passage through the infra-orbital canal. 

The descending palatine branch enters the posterior palatine 
canal and subsequently supplies the hard palate, the gums and 
the palatine glands. It can be felt in the mouth on the inner 
side of the last molar tooth. 

The vidian branch passes through the vidian canal, and sup- 
plies the Eustachian tube, the pharynx and the tympanum. 

The pterygo-palatine branch, so called from the canal through 
which it passes, supplies the Eustachian tube and the pharynx. 

The nasal or spheno-palatine branch, so called from the fora- 
men of that name through which it passes, supplies the mucous 
membrane of the nose, the antrum and the sphenoidal and the 
ethmoidal cells. 

INTERNAL CAROTID ARTERY. 

The internal carotid artery arises at the bifurcation of the 
common carotid artery, on a level with the upper border of the 
thyroid cartilage, and, after ascending through the neck, it passes 
through the carotid canal in the petrous portion of the temporal 
bone, into the cavity of the cranium. 

During its passage through the neck, it lies in front of the 
transverse processes of the cervical vertebrae. After its passage 
through the carotid canal, it ascends along the side of the sella 
turcica and curves upwards by the anterior clinoid process of the 
sphenoid bone. It then pierces the dura mater and divides into 
its terminal branches. 

This vessel is remarkable for the number of abrupt curves that 
it presents in the different portions of its course. These curves 
are explained as an effort on the part of nature to offer a mechan- 



358 ANGIOLOGY. 

ical obstruction to a rapid current of blood entering the brain, 
since increased friction is thus produced and danger of rupture 
of the cerebral capillaries from excessive hearts action is thus ob- 
viated. 

This artery is usually studied as to its course and relations, by 
dividing it into four distinct portions. 1st. The cervical portion 
which includes all of the artery below the carotid canal. 2d. The 
petrous portion, including that part of the artery which lies within 
the carotid canal. 3d. The cavernous portion, which includes 
that part of the artery lying in relation to the cavernous sinus, 
and 4th. The cerebral portion, or the balance of the artery before 
it divides into its terminal branches. 

The internal carotid artery is distributed to the brain, and the 
eye and its appendages. In point of calibre, it equals that of the 
external carotid artery. 
Cervical portion. 

This portion of the internal carotid artery lies at first upon the 
outer side of the external carotid artery 4 , but soon sinks beneath 
the parotid gland, and becomes very deeply situated, as it passes 
behind and underneath that vessel. 

In its course, it is separated from the external carotid artery 
by two muscles, viz., the stylo-glossus and the stylo-pharyngeus 
muscles ; and by two nerves, the glosso-pharyngeal and the pharyn- 
geal branch of the pneumogastric. 

PLAN OF THE RELATIONS OF THE INTERNAL CAROTID ARTERY 

IN THE NECK. 

In front. 

Integument. 

Superficial and deep fascia. 

Muscles \ St y lo -g losseus - 
Muscles., -j Stylo . pharyngeus . 

Nerves \ Glosso-pharyngeal. 

* " ( Pharyngeal branch of the pneumogastric. 



Externally. /internal CaroA Internally. 

Internal jugular vein. ^d Artery. I Pharynx. 

Pneumogastric nerve. \ / Tonsil. 




Ascending pharyngeal artery. 



Behind. 
Rectus capitis anticus major muscle. 
Sympathetic ganglion (upper cervical). 
Superior laryngeal nerve. 



INTERNAL CAROTID ARTERY. 



35$ 



Petrous portion. 

In this portion of the artery, the cavity of the middle ear is in 
the closest relation, being separated from it only by a thin 
lamella of bone, which in a young subject is cribriform, and, in old 
age, is often nearly deficient from absorption. 

The artery is separated from contact with the bony walls of 
the carotid canal by an investing tubular process of the dura 
mater ; but has in direct contact with it the carotid plexus of 
nerves. 

Cavernous portion. 

On reaching the -body of the sphenoid bone, after entering 
the cavity of the cranium, the internal carotid artery enters the 
cavernous sinus, having first perforated a layer of dura mater, 
which forms the outer border of that cavity. 

Within this sinus the following relations are important, and 
may be shown by the following diagram. 

Internally. / \ Externally. 

Internal carotid artery. / Cavernous \ 3rd cranial nerve# 

6th cranial nerve. I Sinus. I 4th cranial nerve. 

Carotid plexus of nerves. \ / Ophthalmic branch of the 5th 

cranial nerve. 






Cerebral portion. 

This portion of the internal carotid artery lies on the outer 
side of the optic nerve, having the 3d cranial nerve (motor oculi) 
external to it, and extends to the inner extremity of the fissure 
of Sylvius. 

The internal carotid artery may be wounded by deep pene- 
trating wounds received within the mouth, from stab wounds of 
the neck, or from gun shot wounds or lacerations, which envolve 
the deeper structures of the neck. It may also occasionally be 
wounded in operations upon the tonsil or may participate in the 
ulceration of severe attacks of supurative tonsilitis. 

Branches. 

The internal carotid artery gives off eight branches as follows : 
one, in the petrous portion ; three, in the cavernous portion ; and 
four, in the cerebral portion. The names of these branches are 
shown in the following table. 



360 ANGIOLOGY. 

A Table of the Branches of the Internal Carotid 

Artery. 



OTID ARTERY. 
(8 branches.) 



f Tn petrous portion . . . .(1 branch).. \ Tympanic. 

INTERNAL CAR- | . ' ( Arterise receptaculi. 

In cavernous poition (3 branches) < Anterior meningeal. 

( Ophthalmic. 
f Anterior cerebral. 

In^^m/^r/^....( 4 branches)J^ iddlecerebraI - . f . 

1 Posterior communicating. 

Anterior choroid. 

Palpebral. 

Lachrymal. 

Supra-orbital. 

Orbital branches (6) \ Ethmoidal, -j p^™; 

Frontal. 
[Nasal. 



Opthalmic artery. 
(13 branches). 



f Muscular., |*g£* 

L Ocular branches (6) \ . . ( Lon S 



Ciliary. . . . \ Short. 

Anterior. 
. Arteria centralis retinae. 



The tympanic branch enters the tympanum through a foramen 
of minute size in the carotid canal. 

The arterice receptaculi include several branches, which are 
distributed to the pituitary body, the Gasserian ganglion, the 
walls of the cavernous sinus and the adjacent dura mater. 

The anterior meningeal branch supplies the dura mater of the 
frontal region of the skull. 

The OPHTHALMIC ARTERY is a large trunk which escapes from 
che cavity of the skull, through the optic foramen, where it lies on 
the outer side of the optic nerve. Within the orbit this vessel 
crosses the optic nerve, to reach the inner side of the orbit, and 
passes forwards to the inner angle of the eye, where it divides 
into two terminal branches, the nasal and frontal, and anasto- 
moses with the facial artery. 

The branches of this artery are twelve in number although 
the number is often given as nine, by leaving out the subdivisions 
of the ethmoidal, muscular and ciliary sets. They are divided 
into two groups called, respectively, the orbital group and the oc- 
ular group. The branches of each of these groups are shown in 
the preceding table. 

The lachrymal branch is the largest branch of the opthalmic 
artery and it supplies the lachrymal gland and conjunctiva of the 
upper eyelid. It anastomoses with the deep temporal, the trans- 
verse facial, the middle meningeal, and the palpebral arteries. 

The supra-obital branch of the ophthalmic artery passes through 



BRA N CHES OF OP THA LMIC A R TER Y. ?>6l 

the supra-orbital foramen in company with the supra-orbital nerve, 
and supplies the pericranium, the muscles and the integument of 
the forehead. 

The ethmoidal arteries are two in number, which pass through 
the ethmoidal foramina, into the cavity of the cranium. They 
supply the dura mater of the brain, the mucous membrane of the 
nose, the ethmoidal cells and the frontal sinuses. 

The palpebral arteries are two in number and form an arterial 
circle around the free margin of the eyelids, and supply the mucous 
membrane of the nasal duct. 

The frontal artery supplies the pericranium, muscles, and in- 
tegument of the frontal region. 

The nasal artery is distributed to the root of the nose, and 
affords a free communication with the nasal and angular branches 
of the facial artery. 

The short ciliary arteries vary from twelve to fifteen in number 
and almost completely enclose the optic nerve. They enter the 
back of the globe of the eye and supply the choroid coat and the 
ciliary processes. 

The long ciliary arteries, two in number also enter at the back 
part of the eye and supply the ciliary ligament. They form two 
arterial circles, one around the circumference, and the other 
around the free margin of the iris, which are connected by inter- 
mediate branches of communication. 

The anterior ciliary arteries form an arterial circle around the 
front part of the eyeball near the circumference of the cornea. 

The muscular branches of the ophthalmic artery are two in 
number and supply the muscles of the orbit. 

The arteria centralis retinae is one of the smallest branches of 
the ophthalmic artery. It pierces the sheath and substance of the 
optic nerve about one-quarter of an inch behind the eye-ball, and 
runs, embedded within it, until it reaches the retina, where it is 
distributed. In the foetus, a small branch of this vessel passes 
directly through the vitreous humor within the posterior chamber 
of the eye, and is distributed to the posterior surface of the cap- 
sule of the lens. 

The anterior cerebral artery is contained in the longitudinal 
fissure of the brain. It is connected to its fellow by an artery 
two lines in length, called the anterior communicating artery. 
This is the shortest artery in the body and forms the anterior 
boundary of the circle of Willis. 

The middle cerebral artery is the largest branch of the internal 
carotid and is a direct continuation of that vessel. It is contained 



362 ANGIOLOGY. 

in the fissure of Sylvius, where it divides into three branches ; one 
supplying the anterior lobe of the brain ; a posterior supplying 
the middle lobe ; and a middle supplying the island of Reil. 
This artery upon the left side is the most frequent seat of em- 
bolic obstruction, since the upward current of blood finds a nearly 
straight channel from the aortic arch to this vessel ; the right side 
presenting a less direct channel on account of the angle at which 
the innominate artery leaves the aortic arch. 

The posterior communicating artery serves to join the internal 
carotid artery with the posterior cerebral branch of the basilar 
artery. This artery helps to form the arterial circle at the base 
of the brain, called the circle of Willis. 

The anterior choroid artery is distributed to the middle cornu 
of the lateral ventricle of the brain. 

Circle of Willis. 

A remarkable anastomosis exists between the vessels at the 
base of the brain by which the circulation not only of the brain 
but also of all structures entering into the formation of the head 
and neck, to a great extent, is equalized ; and by which the re- 
sults of any obliteration of one or even two of the larger vessels 
may be speedily remedied by a corresponding enlargement of the 
others. 

This anastomosis, which is known as the circle of Willis, results 
from a series of communications between the following arteries. 

1. The two anterior cerebral arteries are connected by the an- 

terior communicating artery. 

2. The anterior cerebral arteries, which assist in forming the 

circle are direct branches of the internal carotid artery 
of either side. 

3. The internal carotid arteries of each side are united to the 

two posterior cerebral arteries by the posterior commun- 
icating branches. 

4. The posterior cerebral arteries themselves arise from a single 

trunk, viz., the basilar artery. 

Thus, from before backwards, we perceive the anterior com- 
municating artery, next the two anterior cerebrals, next the in- 
ternal carotid trunks, next the two posterior communicating ar- 
teries, next the two posterior cerebral arteries, and finally the 
basilar artery, where the last mentioned vessels converge. 

Within the space or area, enclosed by this vascular circle, may 
be found the following parts, in their respective order from before 
backwards. 



3^3 



THE CIRCLE OF WILLIS. 

1. The lamina cinerea. 

2. The optic commissure. 

3. The infundibulum. 

4. The tuber cinereum. 

5. The corpora albicantia. 

6. The posterior perforated space. 



ARTERIAL SUPPLY OF SPECIAL REGIONS OF THE 
HEAD AND NECK. 

In recapitulation of the arteries, derived from the principal 
vascular trunks of the head and neck, it may be of service to the 
student to present, in a tabulated form, the various sources of vas- 
cular supply to special structures, which have at times great sur- 
gical interest. 

Vascular Supply of the Meninges of the Brain. 

The meninges of the brain and spinal cord receive arterial 
blood from the following sources. 

1. Anterior meningeal artery (branch of the internal carotid). 

2. Middle meningeal artery (branch of the internal maxillary). 

3. Small meningeal artery (branch of the internal maxillary). 

4. Posterior meningeal artery (branch of the vertebral artery). 

5. Inferior meningeal artery (branch of the occipital artery). 

6. Small branches, which are not specially named but which 

are still distributed to the meninges. Among these 
the more important ones are, 

Branches from the ascending pharangeal arteries. 

Branches from the lachrymal arteries. 

Branches from the posterior ethmoidal arteries. 

Branches from the anterior ethmoidal arteries. 

Branches from the vertebral artery. 
Of these branches the anterior meningeal artery and the men- 
ingeal branches of the two ethmoidal and lachrymal arteries sup- 
ply the anterior fossa of the skull ; the middle and small menin- 
geal and some branches of the ascending pharangeal, which enter 
the skull at the foramen lacerum basis cranii, supply the middle 
fossa ; while the posterior fossa of the skull is supplied by the 
posterior and inferior meningeal arteries, and branches of the 
ascending pharangeal, which enter the cavity of the cranium 
through the jugular and the anterior condyloid foramina. 



3 6 4 



ANGIOLOGY. 



Vascular Supply of the Pharynx. 

The pharynx is supplied with blood by the following vessels. 

1. Inferior or ascending palatine artery (branch of the facial). 

2. Posterior or descending palatine artery (branch of the inter- 

nal maxillary). 

3. Spheno-palatine artery (branch of the internal maxillary). 

4. Pterygopalatine artery (branch of the internal maxillary). 

5. Ascending pharangeal (branch of the internal carotid). 

6. Small branches from the following arteries. 

Dorsalis linguce (branch of the lingual). 

Tonsillar artery ("branch of the facial). 

Vidian artery (branch of the internal maxillary). 

Vascular Supply of the Tympanum. 

The tympanum receives its blood chiefly ^from the following 
sources. 

1. The tympanic branch of the internal maxillary , which enters 

at the Glaserian fissure. 

2. The tympanic branch of the internal carotid, which enters 

through a small foramen within the carotid canal. 

3. The stylo-mastoid artery (a branch of the posterior auricular), 

which enters the acqueductus Fallopii through the 
stylo-mastoid foramen. 

4. The vidian artery (a branch of the internal maxillary), which 

passes through the vidian canal and accompanies the 
large petrossal nerve through the hiatus Fallopii. 

5. The petrosal branch of the middle meningeal artery, which 

enters at the hiatus Fallopii. 

6. Branches from the ascending pharangeal artery, which enter 

the tympanum along the Eustachian tube. 



SURGICAL TRIANGLES OF THE NECK. 365 

SURGICAL TRIANGLES OF THE NECK. 

The vessels of the head and neck, if examined collectively, 
are contained within certain spaces of a triangular form, whose 
boundaries are defined by the borders of certain muscles, and 
whose contents are of great surgical interest, as the various struc- 
tures bearing relation to those vessels which have already been 
separately described, can in this way be studied from a surgical 
standpoint. 

In each of these various triangles important operations are 
being constantly performed and only, by a thorough knowledge 
of their contents and relations of each, can such operations be 
skilfully or safely executed. 

In the chapter of this volume upon the muscles of the neck, 
will be found a diagrammatic illustration of these triangles and sub- 
sequent explanatory text, in which the boundaries and floor of 
each are given. It will be needless therefore to repeat them 
here since the muscular boundaries and the floor of these triangles 
are properly and best considered under the head of myology. 

Without entering, therefore, into a description of the limits 
of the various triangles, the gross contents of each will first be 
enumerated, in order to assist the memory of students and sub- 
sequently the relations of the more important structures will be 
given. 

The INFERIOR CAROTID triangle is situated low down near 
the root of the neck and anterior to the sterno-mastoid muscle. 
It is covered by the integument, the superficial cervical fascia, 
the platysma muscle, the deep cervical fascia, the sterno-thyroid, 
sterno-hyoid muscles and the anterior margin of the tendon of 
"■he sterno-mastoid muscle. 

It contains the following structures which possesses surgical 
importance. 

Common carotid. 

3 Arteries.. -^ Inferior thyroid. 
Vertebral. 



(Int( 

.... ^Ver 
(Mic 



itcrnal jugular. 
3 Veins... . -^Vertebral. 

iddle thyroid, 



6 Nerves 



3 Organs 



Superficialis colli ; branch of cervical plexus). 
Pneumogastric. 

Descendens noni ; (branch of hypoglossal nerve). 
' "J Communicans noni ; (branch of cervical plexus). 
Recurrent laryngeal ; (branch of pneumogastric). 
Sympathetic. 



( Trachea. 

X Thyroid gland. 

( Lower part of 1; 



uynx. 



366 ANGIOLOGY. 

Within this triangle the common carotid artery lies in its 
sheath ; in which are also enclosed the internal jugular vein and 
the pneumogastric nerve, the vein lying outside of the artery and 
the nerve between and behind the artery and the vein. 

In front of and upon this sheath are seen the filaments of the 
descendens and communicans noni nerves ; while, in front also, the 
filaments of the super ficialis colli nerve ramify between the deep 
cervical fascia and the platysma muscle, and the middle thyroid 
vein frequently crosses the artery. 

Behind the sheath are seen the inferior thyroid artery, and the 
recurrent laryngeal nerve ; and the vertebral vein and artery lie 
upon the floor of the triangle between the scalenus anticus and 
the longus colli muscles, below the level of the 6th cervical ver- 
tebra. 

On the inner side of the sheath, the trachea, the lower portion 
of the larynx and the thyroid gland can be discerned. 

Within this triangle the common carotid is tied, if the seat 
of election be below the omo-hyoid muscle. 

The SUPERIOR CAROTID triangle is covered by the integu- 
ment, the superficial cervical fascia, the platysma muscle and the 
deep cervical fascia, and lies immediately above the preceding 
triangle and anterior to the sterno-mastoid muscle. 

It contains the following structures : 

Common carotid (bifurcation of). 

External carotid. 

Internal carotid. 

Superior thyroid. 

Lingual. 

Facial. 

Occipital. 

Ascending pharyngeal. 



8 Arteries.. \ 



["Internal jugular. 
Superior thyroid. 

• Veins... J J&* 

} Occipital. 
^ Pharyngeal. 



8 Nerves. 



Facial branches (cranial). 

Superficiahs colli (branch of cervical plexus). 

Descendens noni (branch of the hypoglossal). 

Hypoglossal (cranial). 

Pneumogastric (cranial). 

Spinal accessoiy (cranial). 

Superior laryngeal (branch of pneumogastric). 

External laryngeal branch of superior laryngeal. 



2 Organs., i Lower part of pharynx. 

& ( Upper part of larynx. 



Within this triangle the three larger vessels of the neck, vi2. 9 
the common, external, and internal carotid arteries, are somewhat 



SUPERIOR CAROTID TRIANGLE. 



367 



concealed from view by the edge of the sterno-mastoid muscle, 
which overlaps them. The external and internal carotids lie, 
side by side, on a line corresponding to the level of the upper 
border of the thyroid cartilage, which corresponds to their point 
of origin ; the external carotid lying to the inner side. 

Above this line are seen, within this triangle, the first five 
branches of the external carotid, three of which (the superior thy- 
roid, lingual, and facial arteries) pass forwards towards the me- 
dian line of the neck ; one passes backwards (the occipital artery) ; 
while the remaining one (the ascending pharyngeal artery) runs 
upwards nearly parallel with, and to the inside of, the internal 
carotid artery. 

The veins, with the exception of one (internal jugular) corres- 
pond to and accompany the arteries of the same name, while the 
internal jugular vein runs in connection with the internal and 
common carotid arteries, lying to the outer side of each, and re- 
ceive the blood from the other five veins contained within this 
triangle. 

The nerves contained within this space are numerous, and of 
great surgical importance. 

Upon the sheath of the common carotid, lies the descendens 
noni nerve, not having yet reached the filaments of the communi- 
cans noni nerve. The hypoglossal nerve curves around the occipital 
artery and crosses in front of both the carotids. 

The sympathetic nerve lies behind the sheath of the common 
carotid; within this sheath, lies the pneumogastric nerve ; and, on 
the outer side of the larger vessels, the spinal accessory nerve runs 
for a short distance, before it pierces the sterno-mastoid muscle. 

The branches of the superficialis colli and facial nerves ramify 
underneath the platysma muscle and above the deep cervical fascia. 
On the inner side of the internal carotid artery, just below the 
hyoid bone, the superior laryngeal nerve may be perceived, on its 
way to the larynx ; while, lower down and in the same relation to 
the artery, the external laryngeal branch of the superior laryngeal 
nerve can be detected. 

The upper part of the larynx and the lower part of the 
pharynx, which lies behind the former, are also perceived on the 
inner wall of this space. 

The SUBMAXILLARY TRIANGLE corresponds to that portion of 
the neck lying immediately below the lower jaw. It is covered 
by the integument, the superficial cervical fascia, the platysma 
muscle, and the deep cervical fascia. 



368 ANGIOLOGY. 

This space contains the following structures: 

Internal carotid. 

External carotid. 

Facial. 

Sub-mental. 

8 Arteries .^ , r , , . , 

Mylo-hyoid. 

Posterior auricular. 

Temporal. 

L Internal maxillary. 

Internal jugular. 

Facial. 

Parotid veins. 
7 Veins. . . \ Temporal. 

I Internal maxillary. 
I Temporo maxillary. 
[_ Posterior auricular. 

f Facial. 

I Pneumogastric. 
5 Nerves. . \ Mylo-hyoid. 

I Glosso-pharyngeal. 
(^Superficial cervical. 

~, , ( Submaxillary gland. 
2 Glands. - ^ Parotid gland. 

In the front portion of this space, the submaxillary gland 
contains, embedded within a groove on its surface, the facial 
artery and vein; and, beneath this gland, lie the submental artery 
and the mylo-hyoid artery and nerve. 

The posterior portion of this triangle is separated from the 
anterior portion by the stylo-maxillary ligament. Within this 
portion of the triangle lies the external carotid artery, deeply im- 
bedded within the parotid gland. This vessel here lies in front 
of, and superficial to, the internal carotid artery. In this situa- 
tion, the facial nerve crosses the internal carotid and sends some 
of its filaments in company with the superficial cervical nerve to 
ramify beneath the platysma muscle. 

Withi?i the substance of the parotid gland, the external carotid 
artery also gives off the posterior auricular branch and divides into 
its two terminal branches, the temporal and internal maxillary 
vessels. 

The internal carotid artery is more deeply situated than the 
external carotid and is separated from it, in this triangle, by the 
stylo-glossus and the stylo-pharyngeus muscles and also by the 
glosso-pharyngeal nerve. It is accompanied by the internal 
jugular vein and the pneumogastric nerve, the vein lying to the 
outside of the internal carotid artery. 

The veins mentioned in the table of contents of the sub- 
maxillary triangle correspond, in most instances, to the arteries 
also contained, although a few of the superficial veins of this 



THE SUBMAXILLARY TRIANGLE. 



3 6 9 



region receive special names from their situation. As veins are 
extremely liable to vary in their situations, nothing can be posi- 
tively asserted as to their exact relations, save in the case of a 
few special veins, as the internal jugular vein for example. 

The OCCIPITAL TRIANGLE is the largest division of the pos- 
terior triangle of the neck. It is covered by the integument, the 
superficial fascia, the platysma muscle and the deep cervical 
fascia. 

Its contents may be thus enumerated: 

I Arteiy. . . \ Transversalis colli. 

Veins \ Transversalis colli vein. 
" " ' ( Posterior external jugular. 

{Ascending branches of the cervical plexus. 
Spinal accessory. 
Descending branches of the cervical plexus. 

Cla ds i "^ c h am °f lymphatics running from the mastoid 

""■( process to the root of the neck. 

Within this surgical triangle these parts are thus arranged. 

The artery runs along the lower portion of the triangle, in a 
direction nearly horizontal, and the transverse cervical vein ac- 
companies it. 

The posterior external jugular vein, passes from above down- 
wards, between the splenius and the trapezius muscles, in a line 
nearly parallel with the posterior margin of the sterno-mastoid 
muscle, till it opens into the external jugular vein, at about its 
centre. 

The spinal accessory nerve is directed obliquely across this 
space, after escaping from the sterno-mastoid muscle, which it 
pierces, till it reaches the trapezius muscle, to which some of its 
terminal filaments are distributed. 

The branches of the cervical plexus are very superficial in their 
situation and ramify subcutaneously over the entire space. 

The SUBCLAVIAN TRIANGLE is much smaller than the preced- 
ing triangle and lies between the inferior border of the posterior 
belly of the omo-hyoid muscle and the clavicle. Its dimensions 
admit of variations in size, being dependent upon, I. The height 
of the omo-hyoid muscle in the neck. 2. The extent of the at- 
tachment of the trapezius muscle. 3. The extent of the clavicu- 
lar portion of the sterno-mastoid muscle, and 4. The position of 
the arm, which, if raised, greatly diminishes the size of this space 
by altering the relative position of the clavicle to the omo-hyoid 
muscle, or if depressed, tends to increase its normal area. 



5 Veins . . . 



37O ANGIOLOGY. 

This space is covered by the integument, the platysma mus- 
cle and the superficial and deep cervical fascia. It contains the 
following structures : 

( Subclavian (3rd portion). 
3 Arteries . s Supra-scapular. 

( Transversalis colli. 

Subclavian (occasionally). 
Supra-scapular. 
Transversalis colli. 
External jugular. 

Small vein crossing the middle of the clavicle from 
the cephalic vein. 

( Descending branches of the cervical plexus. 
^ J Brachial plexus (formed by 5th, 6th, 7th, 8th cer- 

3 JNerve . . < vical and 1st dorsal nerves). 

[ The nerve to the subclavius muscle. 

Glands ■{ Lymphatic glands. 

These various structures are arranged within this triangle in 
the following manner. 

The subclavian artery lies just below the level of the clavicle, 
curving outwards and downwards, from the outer border of the 
scalenus anticus muscle, to the lower border of the first rib. The 
level of this artery is often higher than the normal, and may, in 
extreme cases, reach a point one inch and a half distant from the 
upper border of the clavicle. 

Occasionally also it passes in front of, or pierces the scalenus 
anticus muscle, thus changing or obliterating the limits of its 
three portions. 

The subclavian vein usually lies behind the clavicle, and, for 
that reason, is only occasionally seen in this space. It may, how- 
ever, in extreme cases, reach the highest point at which the 
artery is ever perceived, and, in a few instances, it has been known 
to pass behind the scalenus anticus muscle in connection with the 
subclavian artery. 

The brachial plexus lies above the artery and in close contact 
with it. The supra-scapular vessels run transversely along the 
clavicular margin of this space, and the transversalis colli vessels, 
traverse its upper angle in the same direction. 

The external jugular vein runs vertically downwards, either 
close to, or underneath, the outer margin of the sterno-mastoid 
muscle, and terminates in the subclavian vein. The transversalis 
colli and supra-scapular veins often form a plexus in front of the 
subclavian artery. 



ARTERIES OF THE UPPER EXTREMITY. 

The arterial trunk, which furnishes blood to the upper limb, 
continues undivided from the commencement of the subclavian 
artery, at a point corresponding, on the right side, to the right 
sterno-clavicular articulation, and, on the left side, at the aortic 
arch, till the elbow is reached on either side. This continuous 
vessel however has been given names in different portions of its 
course according to the regions of the body through which it 
passes. This division, however artificial it may be, serves greatly 
to facilitate reference and to aid in the description of the vessel. 

From the commencement of the vessel as far as the outer 
border of the first rib, the name subclavian artery is applied, from 
its position beneath the clavicle ; from the first rib to the lower 
border of the teres major muscle, which marks the termination 
of the axillary space posteriorly, it is named the axillary artery; 
and from this point to the bifurcation at the bend of the elbow it 
is termed the brachial artery. 

THE SUBCLAVIAN ARTERY. 

In most cases, the description of one side serves for both ; but 
this is not true of the subclavian artery since this vessel arises, 
on the two sides, from different points, and therefore causes ex- 
treme variations in the relations of the first portion of the course 
of the subclavian artery of the right and the left side. It has 
been customary therefore to divide the subclavian artery, of each 
side, into three distinct portions, since by so doing the descrip- 
tion of the vessel may be greatly simplified. These three por- 
tions are indicated by the relation which the vessel bears to the 
scalenus anticus muscle ; the first portion extending from the point 
of origin of the subclavian, on each side, to the inner border of 
this muscle ; the second portion, on each side lying behind this 
muscle, as the artery passes over the first rib ; and the third por- 
tion lying to the outside of the external border of the same mus- 
cle and extending to the point of termination of the subclavian 
artery, at the lower border of the first rib. 

Each of these parts will now be examined in detail. The first 
portion of the artery will require, however, a separate description 
for the right and the left side, since in it alone, is there any mate- 
rial difference in the anatomical description of the two vessels. 



372 



A NG 10 LOGY. 



First Portion of the Right Subclavian Artery. 

The subclavian artery upon the right side commences at the 
bifurcation of the innominate, opposite to the sterno-clavicular 
articulation of the right side and terminates at the inner border 
of the scalenus anticus muscle. 

In this portion the artery ascends slightly above the clavicle 
as a rule, although the height of the vessel in the neck varies in 
different subjects, and lies in a direction which points upwards 
and outwards, from its seat of origin. 

In this portion the right subclavian artery presents the follow- 
ing immediate relation to the important structures which sur- 
round it. 

PLAN OF THE RELATIONS OF FIRST PORTION OF RIGHT SUB- 
CLAVIAN ARTERY. 

In front. 

{ Sterno-mastoid (clavicular origin). 
Three muscles. I Sterno-hyoid. 
(Sterno- thyroid. 

rj, . i Internal jugular. 

Two veins... -j Vertebral. 

iPneumogastric. 
Cardiac. 
Phrenic. 



Beneath. 
Pleura. 



Behind. 

,_ ( Recurrent laryngeal. 

Two nerves j Sympathetic. 

Longus colli muscle. 
Transverse process of 7th cervical vertebra. 

These parts bear also to each other, some special relations, 
which are of surgical interest. The origins of the sterno-mastoid, 
sterno-hyoid and sterno-thyroid muscles separate the artery from 
the superficial structures, which have first to be divided in the 
operation for ligation of this portion of the artery. These super- 
ficial structures are the integument, the superficial cervical fascia, 
the platysma muscle and the deep cervical fascia. 

The two large veins (internal jugular and vertebral) and the 




RIGHT SUBCLA VIAN AR TER Y. 373 

three nerves (pneumogastric, phrenic and cardiac) all cross the 
anterior wall of the artery and lie in close relation to it, being' 
situated below the three deep muscles. The pleural covering of 
the lung lies in close relation to the inferior wall of the artery, 
since the apex of that organ rises high up within the neck, arwd it 
should be avoided in attempting to pass a ligature in this locality. 

The subclavian vein lies below the level of the artery, and is 
therefore not mentioned among the structures which bear a direct 
relation with it. The recurrent laryngeal nerve, on this side, winds 
around the subclavian artery and reaches the closest contact with 
it at its posterior surface. 

Behind the artery the sympathetic system of nerves, the longus 
colli muscle, and the transverse processes of the 7th cervical and 
of the 1st dorsal vertebrae, are in close relation but are still sepa- 
rated from it by a cellular interval. 

First Portion of the Left Subclavian Artery. 

The left subclavian artery arises from the end of the transverse 
portion of the arch of the aorta, and extends to the inner border 
of the scalenus anticus muscle. 

From the peculiarity as to its point of origin it differs from 
the first portion of the opposite subclavian artery in its length, 
direction and the structures to which it bears immediate relation. 

It is much longer than the right subclavian in its first portion, 
and instead of arching upwards, it ascends almost vertically from 
within the chest. 

Commencing as it does from the deepest portion of the arch 
of the aorta, this vessel is, at its origin, situated close to the ver- 
tebral column and behind the left lung. The left subclavian pre- 
sents in this portion of the artery the following relations. 



374 ANGIOLOGY. 



PLAN OF THE RELATIONS OF FIRST PORTION OF LEFT SUB- 
CLAVIAN ARTERY. 

In front. 

{Sterno-mastoid. 
Sterno-hyoid. 
Sternothyroid. 

Two veins \ ^ eft inte ™ al J 11 ^ 1 ^ 

Innominate. 



( Pneumogastric. 
Three nerves. . . 1 Phrenic. 
( Cardiac. 
Left carotid artery. 
Lung of left side and pleura. 




Innner side. /r -eft ««w»i«»ii„A Outer side. 

Esophagus, 
rachea. 
Thoracic duct. 



CEsophagus. [ Arterv. I Pleura of left lung. 

Trachea. 



Behind. 
Oesophagus. 
Thoracic duct. 
Vertebral column. 
Longus colli muscle. 
Inferior cervical ganglion of 
the sympathetic system. 

The pneumogastric, phrenic and cardiac nerves He almost par- 
allel with, and in front of the artery. The pleura of the left lung 
invests it on its anterior and lateral wall forming a depression in 
which it rests. The three muscles of the sternal region separate 
it, as on the opposite side, from the integument, the superficial 
cervical fascia, the platysma muscle and the deep cervical fascia. 

The artery, from its deep situation within the chest, also gains 
relations, posteriorly, with the oesophagus, thoracic duct, verte- 
bral column and its longus colli muscle, and the inferior cervical 
ganglion of the sympathetic nervous system ; while, to its inner 
side, the trachea, oesophagus and thoracic duct also bear an in- 
timate relation. 

In order to assist the memory of students in the anatomy of 
this artery, by the aid of contrast, the following arrangement of 
these relations and other points of interest, pertaining to the first 
portion of the subclavian artery of the right and the left side 
may prove of value. 



SUBCLA VIAN ARTERIES. 



375 



Table of Contrast. 



Relations of the first portion of the I Relations of the first portion of the 

RIGHT SUBCLAVIAN ARTERY. LEFT SUBCLAVIAN ARTERY. 

In front. 
Sterno-mastoid (clavicular 



3 Muscles. 



2 Veins. . . . 



3 Nerves. 



Sterno-hyoid. portion.) 

Sterno-thyroid. 

Right internal jugular. 
Vertebral. 

I Pneumogastric. 

•(Phrenic. 

i Cardiac. 



3 Muscles. -{ The same as on right side. 



2 Veins. . . 



Left internal jugular. 
Innominate. 



3 Nerves. . ■{ The same as on the right side. 

i Artery. . . ■{ Left carotid. 
Left lung and pleura. 



7th cervical vertebra. 

„ AT ( Recurrent laryngeal. 

2 Nerves. . •< c ., ^ J ° 

( Sympathetic. 

I Muscle. . -{ Longus colli. 



Behind. 

Vertebral column (dorsal region). 
Inferior sympathetic ganglion of the cer- 
vical region. 
I Muscle (same as on right side). 
CEsophagus. 

Thoracic duct. 

i 

Other Relations. 



Right pleura lies beneath the artery. 

The artery from its direction admits of no 
relations towards the median line of 
the body. 



Leftpleura lies to the outer side of the ar- 
tery, as well as in front of it. 

The artery is related internally to the fol- 
lowing structures : 

1. CEsophagus. 

2. Trachea. 

3. Thoracic duct. 



Length. 



The right subclavian artery varies in the 
length of its first portion from f to i\ 
inches. 



The left subclavian artery varies in the 
length of its first portion from i-| to 3 
inches. 



The right subclavian commences behind 
the right sterno-clavicular articula- 
tion. 



Point of Origin. 

The left subclavian begins at the left ex- 
tremity of the transverse portion cf the 
aortic arch. 



SECOND PORTION OF SUBCLAVIAN ARTERY. 



The second portion of each subclavian artery lies behind the 
scalenus anticus muscle, and is necessarily very short. It forms 
the highest portion of the arch, described by the vessel, and is 
therefore the most distant from the line of the clavicle. This 
portion is less deeply situated than the first portion of the artery. 
Its relations to contiguous structures are as follows : 



376 ANGIOLOGY. 




PLAN OF THE RELATIONS OF SECOND PORTION OF THE SUB- 
CLAVIAN ARTERIES. 

In front. 
I Muscle. . \ Scalenus anticus. 
i Nerve. . . \ Phrenic. 
I Vein. . . . \ Subclavian. 



Above. I Subclavian \ Behw. 

Brachial plexus of nerves. I Artery. I Pleura, 



Behind. 

Scalenus medius muscle. 

Pleura. 

The three structures, mentioned as in front, are situated be- 
neath the superficial layers of the neck, viz., the integument, the 
superficial cervical fascia, the platysma muscle and the deep cer- 
vical fascia. The phrenic nerve and the subclavian vein lie upon 
the anterior surface of the scalenus anticus muscle and therefore 
do not actually touch the artery. The vein, however, is nearer 
the line of the clavicle than the artery at this point. 

Behind the artery, the scalenus medius muscle is in the closest 
relation and the brachial plexus of nerves, which passes between 
the same muscles as the artery, lies above that vessel and situated 
closely to it. Below the artery, the apex of the lung and its 
pleural covering lie in close relation. 

THIRD PORTION OF SUBCLAVIAN ARTERY. 

The third portion of the subclavian artery passes, in a direc- 
tion downwards and outwards, from the external border of the 
scalenus anticus muscle to the lower border of the first rib, where 
it becomes the axillary artery. 

In this part of its course, the artery lies in a small triangular 
space, the sides of which are formed by the scalenus anticus and 
the omo-hyoid muscles, and its base by the clavicle. It is within 
this triangle that the artery approaches nearer to the surface of 
the neck than in any portion of its course, although the artery, 
as it approaches its termination, sinks deeper and passes under 
the clavicle and the subclavius muscle. 

Its relations within this space will be found tabulated below. 



SUBCLA VI AN ARTERY. 



377 




PLAN OF THE RELATIONS OF THIRD PORTION OF THE SUB- 
CLAVIAN ARTERY. 

In front. 

Integument. 

Two fascia., i Superficial cervical. 
( Deep cervical. 

Two muscles < ^f y sma ' 
( Subclavius, 

S External jugular. 
Supra-scapular. 
Transverse cervical. 
Supra- scapular artery. 
Filaments of the cervical plexus. 
Nerve to the subclavius muscle. 
The clavicle. 



Above _ , S u»clav.an N ^^ 

Brachial plexus. I Artery. I ^.^ ^ 

Omo-hyoid muscle. 



Behind. 
Scalenus medius muscle. 

Compression of the subclavian artery must be performed at 
its point of crossing the first rib, and the pressure must be directed 
downwards and inwards to prove effectual. 

Of the numerous structures, which lie in front of the artery, 
the integument, cervical fasciae and the platysma muscle lie su- 
perficially and the nerve filaments of the cervical plexus ramify 
subcutaneously. At the inner side of the artery, the external 
jugidar vein crosses it, and also, at about the same point, the 
supra-scapular and the transverse cervical veins, which often form 
a plexus in front of the artery. 

The subclavian vein lies on a plane below the level of the 
artery and close behind the clavicle. 

The brachial plexus of nerves lies above and to the outer side 
of the artery. The first rib, over which the artery passes lies 
below it and a small nerve supplying the subclavius muscle can 
usually be perceived crossing this portion of the artery. 

Collateral Circulation. 

After direct communication between the head and the axillary 
artery is cut off, by the application of a ligature to the subclavian 
artery, the supply of blood to the arm is obtained by anastomoses 
between certain vessels carrying blood derived from the subclavian 
and arterial branches deriving their supply from other sources. 



378 ANGIOLOGY. 

• These branches of communication vary with the point at 
which the ligature is applied to the subclavian artery. 

Should the first port ioii of that artery be tied, the vertebral 
affords a direct blood supply to the arm through the circle of 
Willis ; and the princeps cervicis (a branch of the occipital artery), 
joins with the profunda cervicis (a branch of the superior inter- 
costal artery). The superior thyroid (a branch of the external 
carotid) also sends blood into the inferior thyroid (a branch of the 
thyroid axis) ; while the superior epigastric (a branch of the inter- 
nal mammary artery) anastomoses with the deep epigastric (a 
branch of the external iliac artery). 

The intercostal branches of the thoracic aorta also anastomose 
with the branches of the axillary artery upon the chest wall. 

If the second portions be ligated, the direct blood supply is no 
longer cut off from the branches of the subclavian, viz., the thy- 
roid axis, the internal mammary, the vertebral, and the superior 
intercostal arteries. The collateral circulation therefore gains in 
the number of pomts of communication, but loses some of those 
previously mentioned. Thus the vertebral no longer becomes of 
aid, since it arises internal to the point of ligature. The infe- 
rior thyroid no longer needs an indirect current from the superior 
thyroid since it receives a direct supply from the subclavian 
artery. The internal mammary no longer needs to draw on the 
deep epigastric for blood, since it now has also its normal supply 
unimpaired. 

The internal mammary artery, however, from its direct sup- 
ply, sends blood to the empty thoracic branches of the axillary. 
The supra-scapular artery (a branch of the thyroid axis) joins 
with the acromio-thoracic (a branch of the axillary). The trans- 
versalis colli (through its posterior scapular branch) sends blood 
to the subscapular artery (a branch of the axillary) ; and the dors- 
alis scapulae branch of the subscapular artery anastomoses with 
the subscapular branch of the thyroid axis. 

To recapitulate then, as a guide to memory, these various 
points of anastomosis after ligation of the subclavian artery has 
been performed we have the following : 



SUBCLA VIAN AR TER Y. ^7g 



When the first portion is tied. 

The subclavian artery receives blood from the circle of Willis through the vertebral 

artery. 
The subclavian artery receives blood from the carotid through the superior thyroid 

artery. 
The subclavian artery receives blood from the carotid through the princeps cervicis 

artery. 
The subclavian artery receives blood from the thoracic aorta through the posterior in- 

tercostals. 
The subclavian artery receives blood from the external iliac through the deep epigastric 

artery. 

B. 

When the second or third portions are tied. 

The supra scapular (branch of thyroid axis) anastomoses with acromio -thoracic (branch 

of axillary). 
The supra scapular (branch of thyroid axis) anastomoses with dorsalis scapulce (branch 

of subscapular). 
The posterior scapular (branch of the subclavian or the transversalis colli) anastomoses 

with subscapular (branch of axillary). 
The posterior scapular (branch of the subclavian or the transversalis colli) anastomoses 

with dorsalis scapulce (branch of subscapular). 
The internal mammary (branch of subclavian) anastomoses with short tho?-acic (branch 

of subscapular). 
The internal mammary (branch of subclavian) anastomoses with long thoracic (branch 

of subscapular). 
The posterior intercostals (branch of thoracic aorta) anastomoses with thoracic branches 

of the axillary. 

BRANCHES OF THE SUBCLAVIAN ARTERY. 

From the subclavian artery, four vessels spring as direct 
branches, although there are seven important arterial trunks, 
which directly and indirectly arise from this source, and which 
require description. 

The following table illustrates not only the four principal 
trunks which arise, but also the distribution of their various 
branches. 



;8o 



ANGIOLOGY. 



A TABLE OF THE BRANCHES OF THE SUB- 
CLAVIAN ARTERY. 



SUBCLAVIAN 
ARTERY. 
(4 branches,) 



Vertebral. 
(7 branches. 



In the neck. 



In the cavity of 
the skull. ' 



Lateral spinal. 
Muscular branches. 

r Posterior meningeal. 
Anterior spinal. 
Posterior spinal. 
Inferior cerebellar. 



f Transverse branches 
Basi- J Anterior cerebellar, 
lar. I Superior cerebellar. 
(^Posterior cerebral. 



Internal mammary. 
(8 branches). 



Thyroid 

AXIS. 

(3 branches.) 



' Superior phrenic. 
Mediastinal. 
Pericardiac. 
Sternal. 

Anterior intercostal. 
Perforating. 
Musculo-phrenic. 
Superior epigastric. 

f Ascending cervical. 
Inferior thyroid. \ J; u 1 

^ Oesophageal. 
Transversalis \ Superficial cervical. 
colli ( Posterior scapular. 



__ Supra scapular. 



4 I Superior intercostal. 



Profunda cervicis. 
Intercostal branches. 



By some anatomists, the posterior scapular artery is given as 
a branch of the 3d portion of the subclavian artery, since it arises 
from that source perhaps as frequently as from the transversalis 
colli artery. It will, however, be described in this volume under 
the latter point of origin. 

Of the four primary branches given off by the subclavian ar- 
tery, three arise from the first portion of the vessel, viz., the 
vertebral, thyroid axis and internal mammary, and one from the 
second portion of the artery, viz, : the superior intercostal. Of 
these four branches, the vertebral arises from the upper and back 
part of the circumference of the vessel ; the thyroid axis from 
the front portion ; the internal mammary from the under or lower 
aspect of the artery, but nearer to its anterior than its posterior 
surface ; and the superior intercostal branch from the lower and 
posterior aspect of the artery, after the subclavian passes beneath 
the scalenus anticus muscle. By some anatomists the superior 
intercostal artery is given as a branch of the first portion upon 
the left side, but it is questionable if the percentage of dissections 
will verify this as the point of normal origin. 



VERTEBRAL ARTERY. 



33i 



The first three branches, upon both sides of the body, arise 
close together, a space, varying usually from one-half oi an inch to 
an inch, existing between the point of origin of the vertebral and 
the commencement of the vessel, upon the right side ; while upon 
the left side, the distance from the point of origin of the sub- 
clavian to the point of origin of the vertebral varies, in the larger 
percentage of cases, from one and a quarter to two and one-eighth 
inches. 

VERTEBRAL ARTERY. 

The vertebral artery arises, in the average of dissections, at a 
point situated about one-third of an inch from the inner border 
of the scalenus anticus muscle towards the median line, upon the 
right side of the body ; while upon the left side, it is almost invar- 
iably present at the point of abrupt change in the course of the 
subclavian artery, as it arches over the first rib, which however 
corresponds to nearly the same relative point. 

The left vertebral artery is usually the larger than the right, 
and, at its point of origin, its axis lies more nearly in the direct 
line of the current of blood than that of the right side. This per- 
haps accounts for the increased size of the left vertebral artery. 

The vertebral artery, upon either side, ascends through a fora- 
men in the transverse process of each of the first six cervical ver- 
tebrae, and after pursuing a winding course at the base of the skull, 
enters the cranium through the foramen magnum and terminates, 
in front of the medulla oblongata, by uniting with its fellow of 
the opposite side to form the basilar artery. 

The vertebral artery, previous to its entrance to the skull, is 
contained within a triangular space, which is bounded, internally 
by the rectus capitis posticus major muscle; externally, by the 
obliquus capitis superior ; and, below, by the obliquus capitis in- 
ferior muscle. 

On the left side of the body, the thoracic duct passes in front 
of the vertebral artery, on its way to empty into the subclavian 
vein. 

Within the canal, formed by the transverse processes of the 
vertebrae, the vertebral artery is accompanied by a plexus of sym- 
pathetic nerves, and by the vertecral vein, which lies in front of 
the artery. 

The cervical nerves, at their escape from the intervertebral 
foramina, lie behind the vertebral artery as it ascends through the 
bony canal. 

Within the cavity of the skull, as the artery winds around the 



382 ANGIOLOGY. 

medulla oblongata, it is located between the hypo-glossal nerve 
and the anterior branch of the suboccipital nerve. 

Branches. 

The branches of the vertebral artery are six in number and 
may be divided into two sets, viz., those given off within the neck 
and those given off within the cranium. The branches comprised 
in each set will be found enumerated in the table of the branches 
of distribution of the subclavian artery on page 380. 

The lateral spinal branches enter the cavity of the spinal axis 
through the intervertebral foramina. 

The muscular branches, which are given off in the vicinity of 
the atlas, supply the deep seated muscles of the cervical region. 

The posterior spinal branch arises from the vertebral artery 
after its entrance to the cranium. It anastomoses, through the 
intervertebral foramina with small cervical and dorsal vessels. 

The anterior spinal branch unites, at the border of the fora- 
men magnum, with the artery of the opposite side to form a com- 
mon trunk. 

The posterior meningeal artery ramifies between the dura mater 
and the bone, in the posterior fossa of the skull. 

The ififerior cerebellar artery is the largest branch of the 
vertebral and arises from that vessel near the pons varolii. It 
passes between the hypo-glossal and the pneumogastric nerves. This 
artery supplies blood to the choroid plexus within the substance 
of the brain. 

BASILAR ARTERY. 

This vessel is formed by the union of the two vertebral arte- 
ries and is so-called, since it lies upon the basilar process of the 
occipital bone. 

It extends from the posterior to the anterior border of the pons 
varolii. 

Branches. 

This artery bifurcates into the two posterior cerebral arteries 
and, in its course, gives off the anterior cerebellar, the posterior 
cerebellar, and transverse branches. 

One of the transverse branches accompanies the auditory nerve 
within the auditory canal, and is called the auditory artery. 

Another of the transverse branches, which is of large size, 
receives the name of the anterior inferior cerebellar artery. 

The superior cerebellar branch and the posterior cerebral artery 
are separated, at their point of origin, by the third cranial nerve. 



BRANCHES OF THYROID AXIS. 



THE THYROID AXIS. 



383 



This large arterial trunk arises from the anterior aspect of the 
subclavian artery, at a point slightly internal to the inner margin 
of the scalenus anticus muscle. Its average length is about one 
quarter of an inch. It divides into three large trunks called as 
follows : 

Inferior thyroid artery. 

Transversalis colli artery. 

Supra-scapular artery. 

INFERIOR THYROID ARTERY. 

This vessel passes beneath the sheath of the common carotid 
artery (which encloses also the jugular vein and the pneumogas- 
tric nerve) and in front of the vertebral artery, before it reaches 
its point of distribution within the body of the thyroid gland. 

The middle cervical ganglion of the sympathetic nerves fre- 
quently lies upon this artery, after it has passed underneath the 
carotid sheath. 

The branches of the inferior thyroid artery are : 
Laryngeal. Oesophageal. 

Tracheal. Ascending cervical. 

The laryngeal branch supplies the mucous membrane of the 
larynx and the muscles of that region. 

The tracheal branch is distributed to the trachea and anast- 
omoses with the bronchial arteries (branches of the thoracic 
aorta). 

The oesophageal branches are distributed to the oesophagus. 

The ascending cervical branch is irregular in its point of origin. 
It ascends the neck in close relation with the phrenic nerve. 

SUPRA-SCAPULAR ARTERY. 

This artery passes downwards and inwards from its point of 
origin, and, under protection of the clavicle, reaches the supra- 
scapular fossa. In its course it crosses the phrenic nerve and 
passes between the subclavian artery and its vein. It anasto- 
moses in the supra-scapular fossa, with the dorsalis scapulae artery 
(a branch of the subscapular) and the acromial thoracic artery 
(a branch of the axillary). It supplies the shoulder joint. 

Its branches are as follows : 

Muscular. Supra-acromial. 

The muscular brandies are distributed to the adjacent muscles 
along its course. 



3§4 



ANGIOLOGY. 



The supra-acromial branch anastomoses, upon the acromion 
process of the scapula, with the acromial thoracic branch of the 
axillary artery. 



THE TRANSVERSALIS COLLI ARTERY. 

This artery is one of the branches of the thyroid axis. It 
crosses the scalenus anticus muscle and the phrenic nerve, passes 
beneath the omo-hyoid muscle, pierces between the main 
branches of the brachial plexus of nerves, and is distributed to 
the trapezius muscle. 

It gives off two principal branches as follows. 

Superficial cervical. Posterior scapular. 

The superficial cervical branch is distributed to muscles, glands, 
and the integument. 

The posterior scapular artery may be either a branch of the 
transversalis colli or of the third portion of the subclavian artery. 
Some authorities report a percentage of relative frequency in 
favor of the latter point as its normal seat of origin. 

This vessel runs downwards along the posterior margin of the 
scapula as far as the inferior angle of that bone. It supplies the 
neighboring muscles of the back and anastomoses with the sub- 
scapular, the supra-scapular and the posterior branches of the 
neighboring intercostal arteries. 

INTERNAL MAMMARY ARTERY. 

This artery arises from the anterior and lower part of the 
subclavian, close to the inner margin of the scalenus anticus mus- 
cle. It passes downwards within the cavity of the thorax, par- 
allel with the edge of the sternum, but lying about one-half an 
inch to the outer side of it. 

At its point of origin, it is covered, like the other large 
branches of the subclavian artery, by the internal jugular vein. 
This vessel also passes behind the subclavian vein and is crossed 
in front, by the phrenic nerve. It is accompanied in the chest by 
two veins for the greater portion of its course, but, in the upper 
part of the chest, these veins unite to form a single vein. 

The internal mammary artery terminates, at the interval be- 
tween the 6th and 7th ribs, by dividing into its two terminal 
branches. 



s uperior in ter costal ar ter y. 385 

Branches. 

The branches of the internal mammary artery are eight in 
number, as follows. 

Comes nervi phrenici. Anterior intercostal. 

(Superior phrenic). 

Pericardiac. Musculo-phrenic. 

Mediastinal. Perforating. 

Sternal. Superior epigastric. 

The superior phrenic branch accompanies the phrenic nerve in 
its course through the chest ; and, like that nerve, is distributed 
to the diaphragm. 

The mediastinal branches supply the thymus glands and the 
connective tissue of the anterior mediastinum. 

The pericardic branches supply the upper portion of the peri- 
cardium. 

The sternal branches supply the triangularis sterni muscle, and 
both surfaces of the sternum. 

The anterior intercostal branches are two in number to each 
intercostal space. They supply the intercostal and pectoral mus- 
cles, and also the mammae and the integument. They anasto- 
mose with the posterior intercostal vessels, which are branches 
of the thoracic aorta. 

The musculo-phrenic branch is one of the terminal branches of 
the internal mammary. It penetrates the diaphragm at the 8th 
or 9th rib, and terminates at the last intercostal space. 

The superior epigastric artery is a terminal branch and a direct 
continuation of the internal mammary vessel. It becomes super- 
ficial upon the wall of the abdomen at the 7th costal cartilage, 
and lies behind the sheath of the rectus abdominis muscle. This 
artery anastomoses with the deep epigastric artery (a branch of the 
external iliac) and with its fellow of the opposite side. 

SUPERIOR INTERCOSTAL ARTERY. 

This artery arises from the posterior part of the, subclavian 
artery, near its lower border and close to the inner border of the 
scalenus anticus muscle. Its course is at first directed backwards. 
It gives off, early in its course, one important branch (the pro- 
funda cervicis) which anastomoses with the princeps cervicis ar- 
tery (a branch of the occipital) and thus establishes an important 
collateral circulation. The main artery bends downwards and 
backwards in front of the neck of the 1st rib and often oi the 2d 
rib, and terminates either in the first or second intercostal space. 



386 ANGIOLOGY. 

Opposite the neck of the 1st rib, the first dorsal ganglion of tlie 
sympathetic system lies upon the inner side of this vessel. 

This vessel sends branches I. To the first or second intercos- 
tal spaces (intercostal branches). 2. To the posterior spinal mus- 
cles, 3. To the spinal cord and its membranes. 

The profunda cervicis branch runs upwards in the neck, be- 
tween the complexus and the semispinalis colli muscles, as high 
as the axis, where it anastomoses with the arteria princeps cervi- 
cis and with branches of the vertebral artery. It supplies the 
muscles in the neighborhood of its course. 

THE AXILLARY ARTERY. 

The axillary artery is a direct continuation of the subclavian 
artery and intervenes between that artery, above, and the brachial 
artery, below. It commences at the lower border of the first rib 
and terminates at the lower border of the latissimus dorsi and teres 
major muscles, which mark, posteriorly, the inferior limit of the 
axilla. In its course, this artery passes through the axillary space ; 
and its direction varies with the relative position of the arm to 
the trunk. 

When the arm hangs freely by the side, the artery describes 
a curve whose concavity looks downwards and inwards towards 
the chest ; while, when the arm is extended at a right angle to 
the body, this vessel is nearly straight, and, if the limb be eleva- 
vated to a perpendicular position, the artery is rendered concave 
with its concavity looking upward. 

This artery is deeply seated during the upper portion of its 
course, but becomes superficial near its point of termination, and 
most markedly so when the arm is raised. At the lower portion 
of the axillary space, therefore, pressure can be readily applied to 
the artery and its circulation easily controlled. This pressure 
should however always be directed outwards, since the humerus 
alone affords a resistance sufficient to ensure compression of the 
vessel. 

This vessel is usually described as consisting of three distinct 
portions, which, like the subdivisions of the subclavian artery, 
depend upon the relation of the vessel to a muscle, viz., the pec- 
poralis minor muscle. 

The first portion of the artery lies above this muscle ; the 
second portioit lies beneath it ; and the third portion lies below it. 

These three portions differ in their relations, and in their sur- 
gical importance. They will therefore be considered separately. 



THE AXILLAE V AR TER Y. 



387 



RELATIONS OF THE FIRST PORTION OF THE AXILLARY ARTERY. 

In front. 

Pectoralis major muscle. 

Subclavius muscle. 

Cephalic vein. 

Costo-coracoid membrane. 



Outer side. 
Brachial plexus. 




Inner side. 
Axillary vein. 



Behind. 

1st intercostal muscle. 

1st serration of the serratus magnus. 

Posterior thoracic nerve. 

1st intercostal space. 

The second portion of the axillary artery lies behind the pecto- 
ralis minor muscle. 



RELATIONS OF THE SECOND PORTION OF AXILLARY ARTERY. 

In front. 

Muscles \ Pectoralis ma J° r - 
Muscles. . . i Pectoralis minon 



Outer side. 
Outer cord of brachial plexus. 




Inner side. 
Axillary vein. 
Inner cord of brachial plexus. 



Behind. 
Subcapularis muscle. 
Posterior cord of brachial plexus. 

The third portion of the axillary artery lies below the pecto- 
ralis minor muscle. 



388 ANGIOLOGY. 



RELATIONS OF THE THIRD PORTION OF THE AXILLARY ARTERY. 

In front, 
Pectoralis major muscle. 



Outer side. / \ Inner side. 

i M rl" / Axillary \ 

NerveS - ' J External cutaneous. Artery. Nerves. . j {"^ ^^ 

Coraco-brachialis muscle. \ 3rd portion. I Axillary vein. 



Behind. 

L Teres major. 
Muscles. . . -j Latissimus dorsi. 
( Subscapularis. 
Musculo-spiral. 
2 Circumflex. 




Nerves. . . . 



These plans of relations show, in detail, the following ana- 
tomical facts worthy of memory. 

1. The axillary vein lies internal to the artery in each of its 

three portions. 

2. The brachial plexus of nerves lies to the outer side of the 

first portion, surrounds the second portion with its 
three cords, and surrounds the third portion with its 
terminal branches. 

3. The pectoralis major muscle covers the entire artery on its 

anterior aspect. 

4. The pectoralis minor muscle bears relation only to the second 

portion of the vessel. 

5. The cephalic vein, which joins the axillary vein at the 

level of the lower margin of the deltoid muscle, is in 

relation only with the first portion of the axillary 

artery. 

In the plan of relations of each of the three portions of the 

axillary artery, the individual mention of the integument and the 

fascia which invests the structures covering each and every portion 

of the vessel, have been omitted ; since they must of necessity 

be understood to exist and since they possess no special interest. 

THE AXILLARY SPACE. 

The axilla or the axillary space, through which the axillary 
artery passes, is pyramidal in form, its apex being above and its 
base corresponding to the integument and fascia which binds tiie 
arm to the side of the trunk. 



THE AXILLARY SPACE. 



33' 



This space is situated between the arm and the lateral wall 
of the chest, and is covered in front by the pectoral muscles. 
Its boundaries are as follows : 



In front. . . •< 



2 Muscles. 



Pectoralis major. 
Pectoralis minor. 



Costo coracoid membrane. 

i Teres major. 
Latissimus dorsi. 
Subscapularis. 
The 1st, 2nd, 3rd, and 4th ribs. 
Internally.. \ Muscles \ The first four interc ostals. 
\ Serratus magnus. 
The Humerus. 
Externally. \ o M , j Coraco-brachialis. 

' I Biceps flexor cubiti. 



-1 



The contents of this space may be enumerated in groups, 
before the separate relation and position of each structure is 
considered. 



Contents of the Axillary Space. 



A. 8 Arteries 



j Axillary artery and 
I branches ...... 



B. 9 Veins 



C. 16 Nerves, counting 
the 3 cords of the-{ 
brachial plexus.... 



f Superior thoracic. 
I Acromio-thoracic. 
its 7 ' Thoracica longa. 
-{ Thoracica alaris. 
Subscapular. 
External circumflex. 
^Internal circumflex. 
C Axillary. 

•j Cephalic. [tioned. 

( 7 Veins corresponding to the arterial branches above raen- 

( Brachial plexus (the 3 cords). 

f Internal anterior thoracic. 
External anterior thoracic. 
Internal cutaneous. 
External cutaneous (musculo- 
cutaneous). 
Ulnar. 
Median. 
Musculo-spiral. 
Circumflex. 
3 Subscapular. 
Posterior thoracic nerve. 
Intercosto-humeral nerve. 



12 branches of brachial 



plexus. 



D. Glands : -{ Numerous scattered lymphatics. 

E. Abundant fat and areolar tissue. 

Position of the various structures. 

The axillary artery and vein and the brachial flex us of nerves 
extend, in an oblique position, along the outer wall of the axillary 
space, from its apex to its base, and are placed much nearer to the 
anterior wall than to the posterior. 

The vein lies to the inner side of the artery and almost en- 
tirely conceals it. 



3Q ANGIOLOGY, 

The thoracic branches of the axillary artery and their accom- 
panying veins lie close to the pectoral muscles, which form the 
anterior wall of the space, and the long thoracic artery runs close 
to the lower border of that muscle. 

In the back part of the space, in contact with the lower por- 
tion of the subscapularis muscle, lie the subscapular artery and 
vein ; and the three subscapular nerves are distributed to the mus- 
cles of this locality. Winding around the lower border of this 
muscle, the dorsalis-scapulce artery (a branch of the subscapular) 
and its accompanying vein can be perceived ; and, at the outer 
extremity of the muscle near the shoulder joint, the posterior cir- 
cumflex artery and vein and the circumflex nerve curve backwards 
towards the shoulder. 

Upon the inner or thoracic side of the axilla no large vessels 
exist, but the posterior thoracic and the inter costo-humeral nerves 
can be here detected. The former of these nerves supplies the 
serratus magnus muscle and is often called the " external re- 
spiratory nerve of Bell," since it lies external to the chest and 
affects inspiration, and was so named by Bell in consequence. 
The intercosto-humeral nerve is a branch of the second inter- 
costal nerve which crosses the axillary space and descends along 
the inner side of the arm, to join the lesser internal cutaneous 
nerve. 

BRANCHES OF THE AXILLARY ARTERY. 

The branches of the axillary artery are seven in number, two 
of which are given off from the first portion of the vessel, two 
from the second portion, and three from the third portion. 

These branches are as follows : 

From ist portion (2) \ Superior thoracic. 

f v ' {. Acromial thoracic. 

x? ~ j j. *• r~\ S Thoracic longa. 

From 2nd portion. . . . (2) j Thorzc[c ^ 

Subscapular. 
From ^rd portion. ... (3) -l Anterior circumflex. 



Total, 



Posterior circumflex. 



We thus have four branches (those arising from the first and 
second portions of the artery) which are distributed to the mus- 
cles of the external aspect of the chest ; one large branch (the 
subscapular) to the muscles of the shoulder ; and two smaller ves- 
sels (the circumflex) which supply the shoulder joint and the 
upper portion of the arm. 



BRANCHES OF AXILLARY ARTERY. 



391 



The superior thoracic branch is small in size, and arises either 
' from the axillary artery as a direct branch, or from a trunk in 
common with the acromial thoracic. Its seat of origin is usually 
just above the upper border of the pectoralis minor muscle. It 
passes forwards and inwards between the pectoral muscles 
and is distributed to these muscles and the wall of the chest. 
It anastomoses with branches of the internal mammary artery, 
and the intercostal vessels of the first and second intercostal 
spaces. 

The acromial thoracic branch arises from the anterior aspect 
of the axillary artery, and is a large and, by far the most con- 
stant branch of this vessel. It passes forwards at the level of the 
upper border of the pectoralis minor muscle, and soon divides into 
two sets of branches which pass in opposite directions, one going 
inwards to the chest wall, and the other outwards to the acromion 
process of the scapula. Its thoracic branches supply the serratus 
magnus and the pectoral muscles, and anastomose with the inter- 
nal mammary and intercostal arteries, and with the thoracic 
branches of the axillary. The acromial branches may be divided 
into an ascending and a descending set. The former pass upwards 
to the upper surface of the acromion process, and there anasto- 
mose with branches of the supra-scapular and posterior circum- 
flex arteries. The latter pass downwards, in company with the 
cephalic vein, in the interval formed between the inferior edge of 
the deltoid and the substance of the pectoralis major muscle, and 
sends branches of nutrition to both of these muscles during its 
descent. 

The thoracica longa runs along the lower border of the pec- 
toralis minor muscle in a direction forwards and inwards till the 
mammary gland is reached. It has been called by some anato- 
mists the " external mammary artery " from this peculiarity of 
course and distribution. It sends branches to the serratus mag- 
nus and the pectoralis major and minor muscles, and anastomoses 
with the intercostals and the internal mammary arteries. It sends 
also branches to the lymphatic glands and the cellular tissue of 
the axillary space. 

The thoracica alaris is often wanting. It is distributed, when 
present, to the glands and areolar tissue of the axilla. Its place 
is supplied, when the artery is wanting, by branches of the sub- 
scapular and the acromial and long thoracic arteries. 

The SUBSCAPULAR ARTERY is the largest branch of the axil- 
lary. It arises from that vessel close to the lower border of the 
subscapular muscle, and is the last branch of the second portion 



392 



ANGIOLOGY. 



of the axillary artery. It proceeds along the lower border of the 
subscapular muscle, in a direction backwards and downwards, and 
gives off, midway in its course, a large vessel the dorsalis scapulce 
branch. From this point it extends, considerably diminished in 
size, to the inferior angle of the scapula, accompanied by the sub- 
scapular nerve. This artery supplies the subscapular, serratus 
magnus, teres major and latissimus dorsi muscles, and anasto- 
moses directly with the posterior scapular branch of the trans- 
versalis colli artery. 

The dorsalis scapulas branch turns backwards from the sub- 
scapular artery, about one inch and a half from the point of ori- 
gin of that vessel. It is larger than the direct continuation of 
the subscapular. It leaves the axilla through a triangular space 
bounded, above, by the teres minor; below, by the teres major; 
and in front, by the long head of the triceps. 

Three sets of branches are then given off by the dorsalis 
scapulae, one to the subscapular fossa, one to the infra-spinous 
fossa and one to the axillary border of the scapula. 

The first set supplies the subscapular muscle and anastomoses 
with the posterior scapular and supra-scapular vessels. The 
second set (properly a continuation of the vessel itself) supplies, 
after winding around the axillary border of the scapula, the con- 
tents of the infra-spinous fossa; while the third or median branch 
runs along the axillary border of the scapula, passing between the 
teres major and minor muscles and anastomoses, at the inferior 
angle of the bone, with the posterior scapular artery. 

The circumflex arteries are the two last branches of the axillary 
artery. They arise from the third portion of that vessel, below 
the pectoralis minor muscle close to the commencement of the 
brachial artery, and are called circumflex from the course which 
they take around the neck of the humerus. They are distin- 
guished as anterior and posterior from the direction which they 
respectively take around the bone. 

The posterior circumflex artery is the larger of the two vessels. 
It passes backwards immediately after its origin and winds around 
the humerus, lying in a quadrilateral space situated between the 
bone and the long head of the triceps muscle, and bounded above 
by the teres minor and below by the teres major muscles. It is 
accompanied by the circumflex nerve. This artery terminates 
within the deltoid muscle and upon the shoulder joint. It an- 
astomoses with the anterior circumflex, the acromial thoracic and 
the supra-scapular arteries. 

The anterior circumflex artery arises lower down than the pos- 



BRACHIAL ARTERY. 



393 



terior circumflex and is smaller in its size. It passes outwards 
and forwards under the coraco-brachialis and the inner head of 
the biceps muscle, and thus reaches the bicipital groove of the 
humerus. At this point, it usually divides into two branches, 
one of which passes upwards along the long head of the biceps 
muscle and is distributed to the shoulder joint and the head of the 
bone; while the other continues outwards in its original direc- 
tion, and, after supplying the deltoid muscle, anastomoses with 
the posterior circumflex and the acromio thoracic vessels. 

In the accompanying table is represented, in a tabulated form, 
the branches of the axillary artery which are given off in each of 
its three portions, as well as the more important sub-divisions of 
each. 

A Table of the Branches of the Axillary Artery. 



{Superior thoracic. 



Axillary 

Artery. 

(7 branches.) 



Acromial thoracic. 



SThoracica longa. 
Thoracica alaris. 
Subscapular. 

T ., , . ,. , N \ Posterior circumflex. 

In its yrd portion*?) Anterior circumflex# 



( Acromial branches. 
< Thoracic branches. 
( Humeral branches. 



■{ Dorsalis scapulae. 



Total, 7 



BRACHIAL ARTERY. 



The brachial artery is a direct continuation of the axillary 
artery. It commences at the lower border of the tendons of the 
teres major and latissimus dorsi muscles, which form the posterior 
boundary of the axillary space; and divides into the radial and 
ulnar arteries at a point opposite the neck of the radius, which is 
situated about half an inch below the bend of the elbow. 

This artery runs in a groove on the inner and anterior aspects 
of the arm, and its course may be represented by a line drawn 
from the centre of the axillary space to a point midway between 
the condyles of the humerus. It is in relation with the inner 
borders of the coraco-brachialis and biceps muscles ; and the latter 
muscle, whose outlines are very distinct upon the arm, is used as 
an anatomical guide to the artery. 

Relations. 

/;/ front of this artery, the median nerve passes, at about the 
centre of its course ; since this nerve crosses from the outer to 
the inner side of the vessel. 



394 



ANGIOLOGY. 



Behind the artery, the superior profunda branch takes its origin 
and the musculo- spiral nerve is in intimate relation. 

On the inner side of the artery, the internal cutaneous nerve 
and the basilic vein are in relation, for the greater portion of its 
course ; while, in its upper part, the ulnar nerve is in close re- 
lation, and, in its lower part, the median nerve is also in close 
contact. 

On the outer side of the artery, the humerus is in close relation, 
as well as the coraco-brachialis and biceps muscles. 

At the bend of the elbow, the brachial artery has relations in 
front, with the median basilic vein, the anterior branches of the 
internal cutaneous nerve and the bicipital fascia. Behind the 
vessel, the elbow joint and the brachialis anticus muscle are per- 
ceived. On the inner side of the artery, the pronator radii teres 
muscle and the median nerve are present ; while on the outer side 
of the artery, the tendon of the biceps, the supinator longus, 
and the musculo-cutaneous and the musculo-spiral nerves are 
present. 

The brachial artery can be most effectually compressed at 
about its centre, since it lies in close relation to the tendon of the 
coraco-brachialis muscle at this point. 

The relations of the brachial artery, at the bend of the elbow, 
are frequently designated, to assist the memory of students, by 
the three letters T. A. N., which represent, from without inwards, 
the following parts, viz., I. Tendon of biceps. 2. Artery. 3. 
Median nerve. 

Branches. 

The branches of the brachial artery, including the two ter- 
minal branches, are seven in number as enumerated in the fol- 
lowing table : 

A Table of the Branches of the Brachial Artery. 

1 [Muscular (coraco-brachialis, biceps, brachialis anticus.) 

2 I Nutrient branch to humerus. 
Brachial Artery. J I Superior profunda 



(7 branches.) 



Inferior profunda. 

5 I Anastomotica magna. 

6 Ulnar. . ( ^ . , , 
7LRADiA L J Termmalbranches - 



The muscular branches are irregular in their number and point 
of origin, and are distributed to the coraco-brachialis, biceps, and 
brachialis anticus muscles. 

The nutrient artery supplies the humerus with blood and 



RADIAL ARTERY. 



395 



enters the nutrient canal of that bone, passing downwards towards 
the elbow joint. 

The superior profunda branch accompanies the musculo-spiral 
nerve in the groove of the same name. It gives an articular 
branch to the elbow joint. 

The inferior profunda branch bears a close relation to the 
ulnar nerve. 

The anastomotica magna forms an arch, above the olecranon 
fossa of the humerus, with the articular branch of the superior 
profunda artery. 

The last three branches of the brachial artery, by anastomosis 
with each other and with recurrent branches from the vessels of 
the forearm, afford nutrition to the elbow joint and the investing 
structures. 

If compression of the brachial artery is required in the upper 
part of the arm, the force should be directed upon the artery 
from within outwards ; and, if in the lower part of the arm, from 
before backwards. The most favorable situation, however, is near 
the point of insertion of the coraco-brachialis muscle. 

The lower part of the brachial artery, on account of its rela- 
tion to the veins most commonly opened in venesection, is of 
great surgical interest. The median basilic vein, which is the 
largest and most prominent, lies in close relation with the brachial 
artery, and, in case it should be selected for the operation, that 
portion of the vein which is not in contact with the artery, should 
be opened. 

RADIAL ARTERY. 

The radial artery is the smallest of the two terminal branches 
of the brachial artery, and takes its origin at a point, one-half of 
an inch below the bend of the elbow. It passes down along the 
outer side of the anterior surface of the forearm to the styloid 
process of the radius. It then curves around the outer side of 
the carpus beneath the extensor tendons of the thumb, to the 
upper part of the first interosseous space of the hand, where it 
passes between the two heads of the abductor indicis muscle ; then 
over the bases of the metacarpal bones, passing beneath the 
flexor tendons, the lumbricales muscles and the nerves of the 
palm of the hand, till it reaches the base of the 5th metacarpal 
bone, where it inosculates with the communicating branch oi the 
ulnar artery, and thus forms the deep palmar arch. 

The deep palmar arch lies about a finger's breadth above the 



396 ANGIOLOGY. 

level of the superficial palmar arch, and in making incisions in 
the palm of the hand for pus, it is well to remember that the 
superficial palmar arch lies at about the junction of the inferior 
and middle thirds of the palm ; and that the middle line of the 
individual fingers is the line of safety, below the level of the arch, 
since the digital arteries run in the spaces between the metacar- 
pal bones. 

Relations. 

The relations of this artery within the forearm are principally- 
muscular, except in the middle third of the artery, where the 
radial nerve lies in close relation with the outer side of the vessel. 

The radial artery is frequently ligated in cases of wounds 
either of its trunk or of some of its branches or in case of aneur- 
ism. If the artery should be tied in its middle third the radial 
nerve and the veins which accompany the artery must be 
avoided. 

Branches. 

The radial artery gives off twelve distinct branches ; four of 
which are given off in the forearm ; four at the back of the wrist, 
and four in the palm of the hand. The following table gives the 
names and location of these various branches. 

A Table of the Branches of the Radial Artery. 

f Radial recurrent. 

T ,1 /• / „\ j Muscular branches. 

In the forearm. (4) < A . . , 

J Kr ' Anterior carpal. 

[_ Superficialis volse. 

f Posterior carpal. \ &* * orsa J .interosseous. 

( 4tn dorsal interosseous. 

At back of wrist (4) \ Metacarpal — or 2nd dorsal interosseus. 



Radial Artery. 
(12 branches.) 



I Dorsalis pollicis. j Correspond to a 1st dor- 
[ Dorsalis indicis. \ sal interosseous. 

fPrinceps pollicis. ( Correspond to a 1st pal- 
In the palm of J Radialis indicis. ( mar interosseous, 
the hand. . . (4) | Perforating — (3 in number). 

— [_ Deep palmar interossei — (3 or 4 in number). 
Total, 12 

The recurrent branch of the radial anastomoses with the supe- 
rior profunda and the interosseous recurrent arteries. 

The muscular branches of the radial artery are distributed to 
the muscles on either side of it. 

The anterior carpal branch passes beneath the deep flexor 
tendons, and, with the anterior carpal branch of the ulnar artery, 
forms an anastomosis, which gives off branches to the articulations 
of the carpus. 



ULNAR ARTERY. 



397 



The superficialis voice branch completes, by its junction with 
the. main trunk of the ulnar artery, the super ficial palmar arch. 

The posterior carpal branch, by anastomosing with the poste- 
rior carpal branch of the ulnar artery, forms the posterior carpal 
arch, beneath the extensor tendons of the forearm. This arch 
gives off dorsal interosseous branches to the third and fourth spaces 
of the hand, which anastomose with the perforating branches 
of the deep palmar arch. 

The metacarpal branch corresponds to the dorsal interosseous 
artery of the second space. It arises beneath the extensor ten- 
dons of the thumb. 

The dorsalis indicis and the dorsalis pollicis, correspond to- 
gether, to a first dorsal interosseous artery, supplying the back 
of the thumb and the outer side of the back of the index finger. 

The princeps pollicis and the radialis indicis corresponds to- 
gether, to a first palmar interosseous artery, supplying both sides 
of the palmar surface of the thumb and the outer side of the front 
part of the index finger. 

The perforating branches of the radial artery are three in num- 
ber and pass through the three inner interosseous spaces to an- 
astomose with the corresponding dorsal interosseous arteries. 

The deep palmar interosseous branches of the radial artery are 
usually three or four in number. They descend in front of the 
interosseous spaces, and, at the base of the fingers, join with the 
superficial palmar interosseous branches from the superficial pal- 
mar arch, and then bifurcate to form digital branches to three and 
a half fingers on the inner side of the hand. 

ULNAR ARTERY. 

The ulnar artery is the largest branch of bifurcation of the 
brachial artery, and arises, like the radial artery, from a point 
opposite the neck of the radius or half an inch below the bend of 
the elbow. 

This artery is deeply situated, till it reaches the middle of the 
inner border of the forearm, where it becomes superficial and en- 
ters into close relation with the ulnar nerve. It crosses the ante- 
rior annular ligament of the wrist, on the outer side of the pisi- 
form bone and slightly in front of the ulnar nerve. From this 
point the ulnar artery crosses the palm of the hand, in front of 
the flexor tendons and the terminal filaments of the median an i 
ulnar nerves, and, by joining with the superficialis voice branch of 
the radial, it forms the superficial palmar arch. 



398 



ANGIOLOGY. 



The superficial palmar arch lies on a level with the lower bor- 
der of the thumb, if abducted, and a finger's breadth below the 
deep palmar arch. 

Branches. 

The ulnar artery gives off seven branches as follows : In the 
forearm, three branches ; at the wrist, two branches ; in the 
hand, two branches. 

The following table gives the name and situation of each of 
these seven branches. 

A TABLE OF THE BRANCHES OF THE ULNAR 

ARTERY. 

( Anterior ulnar recurrent. 
I Posterior ulnar recurrent. 
In the forearm. (3)^ ( Anterior. 



■! 

. . f v ( Anterior carpal 
(7 branches.) i At the wrist (2) j posterior ^ 



Ulnar Artery. 



Interosseous. Vt» . ■ ■ ( Recurrent m- 

Postenor. . { 

terosseous. 



( Deep or communicating branch. 
In the hand. (2) •< Digital (superficial palmar interossei) — usual- 
— ( ly four in number. 
Total, 7 

The anterior recurrent branch of the ulnar is small, and 
passes between the pronator radii teres and the branchialis anti- 
cus muscle, on its way to the elbow joint. 

The posterior recurrent branch of the ulnar artery is larger in 
size than the preceding branch, and passes beneath the flexor 
sublimis digitorum and flexor carpi ulnaris muscles, on its way 
to the elbow joint. 

The interosseous branch is one inch in length and divides, at 
the upper border of the interosseous membrane, into two trunks 
called the anterior and posterior interosseous arteries. 

The anterior interosseous artery is in close relation with the 
corresponding branch of the median nerve, upon the 
anterior surface of the interosseous membrane. 
The posterior interosseous artery gives off an interosseous re- 
current branch, which ascends to the elbow joint ; and 
the main artery joins the posterior carpal arch, formed 
by the posterior carpal branches of the radial and 
ulnar arteries. 
The anterior and posterior interosseous arteries are given off 
from the main trunk of the interosseous artery at a point situa- 
ted about two inches below the elbow joint ; so that in amputation 



ARTERIES OF THE TRUNK. 



399 



of the forearm, made in the region of four inches below the joint? 
four arteries of medium calibre would require a ligature. 

The anterior carpal branch of the ulnar joins, beneath the 
deep flexor tendons, the same branch of the radial artery. 

The posterior carpal branch of the ulnar artery helps to form 
the posterior carpal arch beneath the extensor tendons of the 
forearm. 

The communicating branch of the ulnar artery, by its junction 
with the main trunk of the radial artery, completes the deep pal- 
mar arch. 

The super ficial palmar interosseous branches, called also digital 
branches, are usually four in number, and join with the deep pal- 
mar interosseous branches which arise from the deep palmar arch. 
The trunks so formed divide, at the clefts between the fingers, to 
form digital branches to three and a half fingers on the inner 
side of the hand. 



ARTERIES OF THE TRUNK. 
THORACIC AORTA. 

The aorta, at the termination of the descending portion of the 
arch, descends through the posterior mediastinum of the chest, 
curving slightly forwards and towards the right side, and passing 
through the aortic opening of the diaphragm, situated in front of 
the 1 2th dorsal vertebra, it becomes the abdominal aorta. 

The so-called thoracic portion of the aorta exclusive of the 
arch which is properly a part of the thoracic aorta, may then be 
said to extend from the lower border of the 4th dorsal vertebra to 
the 1 2th dorsal vertebra. 

Relations. 

The dorsal portion of the thoracic aorta has the following re- 
lations, within the thorax. 



40o 



ANGIOLOGY. 



PLAN OF THE RELATIONS OF THE THORARIC AORTA. 

In front. 
Left pulmonary artery. 
Left bronchus. 
Pericardium. 
CEsophagus — (in lower portion). 



Right side. 
CEsophagus (above). 
Vena azygos major. 
Thoracic duct. 




Left side. 
Pleura. 
Left lung. 
CEsophagus (below). 



Behind. 
Vertebral column. 
Vena azygos minor. 



It will be perceived that the oesophagus bears a triple relation 
to this vessel, being situated in front, and on the left and right 
sides of the artery. This seeming contradiction is due to the fact 
that the oesophagus constantly alters its relation to the thoracic 
aorta, on account of the curve taken by that vessel in its descent 



through the chest. 

Branches. 

In the following table are enumerated the five sets of branches 
of the thoracic aorta and their points of distribution. 

A TABLE OF THE BRANCHES OF THE THORACIC 

AORTA. 



THORACIC 

AORTA. 
(5 sets of 
branches). 



'Pericardiac (irregular in number and location). 

t> ~^ ttt .t /\ i Right bronchial. 
BRONCHIAL. (2) ] L eft bronchial. 

Oesophageal (four or five in number). 
^ Posterior mediastinal (several small branches). 

Aortic Intercos- I Anterior branch, j gg**?* «jjgf. 
tals (10 on each \ . 

s id e ) # ( ( Muscular branches. 

Posterior branch. •< Spinal branches to 
( spinal cord. 

The pericardiac branches are small and irregular in their origin 
and number. They are distributed to the pericardium. 

The bronchial arteries are the nutrient vessels of the lungs, and 
vary in number, size, and origin. That of the right side arises 
from the first aortic intercostal ; or, by a common trunk with the 
left bronchial, from the front of the thoracic aorta. Those of the 
left side, usually two in number, arise from the thoracic aorta, one 



ARTERIES OF THE THORAX. 40I 

a little lower than the other. Each vessel is directed to the back 
part of the corresponding bronchus, along which they run, divid- 
ing and subdividing, upon the bronchial tubes ; and supplying 
them, the cellular tissue of the lungs, the bronchial glands, and 
the oesophagus. 

The (esophageal branches are usually four ox five in number and 
are given off from the anterior aspect of the aorta. 

The posterior mediastinal branches are distributed to the 
glands and the cellular tissue of the mediastinum. 

The aortic intercostal arteries are usually ten in number upon 
each side and are given off from the back of the aorta. Each in- 
tercostal artery divides into an anterior and a posterior branch. 

The anterior branch or proper intercostal branch divides be- 
tween the two intercostal muscles into branches, which supply 
the ribs. 

The posterior or dorsal branch divides into spinal branches, 
which enter the intervertebral foramina and are distributed to 
the spinal cord and its membranes ; and muscular branches which 
are distributed to the deep muscles of the back. 

ABDOMINAL AORTA. 

The abdominal aorta extends from the aortic opening, in front 
of the 1 2th dorsal vertebra, to the body of the 4th lumbar verte- 
bra, where it bifurcates into the two common iliac arteries. 

In its course, it curves slightly backwards and towards the left 
side. Its greatest convexity corresponds to the 3d lumbar verte- 
bra. It is about four inches in length. 



402 



ANGI0L0GY. 



PLAN OF THE RELATIONS OF THE ABDOMINAL AORTA. 

In front. 
Lesser omentum and stomach. 
Branches of cceliac axis and solar plexus 
Splenic vein. 
Pancreas. 
Left renal vein. 
Transverse duodenum. 
Mesentery. 
Aortic plexus. 



Right side. 
Right crus of diaphragm. 
Inferior vena cava, 
Vena azygos. 
Thoracic duct. 
Right semilunar ganglion. 




Left side. 
Sympathetic nerve. 
Left semilunar ganglion. 



Behind. 
Left lumbar veins. 
Receptaculum chyli. 
Thoracic duct. 
Vertebral column. 



The abdominal aorta divides into its two terminal branches, 
the two common iliac arteries, opposite a point situated on the 
exterior of the abdomen at about one inch and a half below the 
umbilicus. This point also corresponds to the level of the highest 
part of the crest of the ilium. 

The abdominal aorta can be compressed with the least danger 
to surrounding tissues and with the greatest ease, at a point situ- 
ated one inch below and slightly to the left of the umbilicus, since 
at this point the aorta approaches nearest to the anterior wall of 
the abdomen. 
Branches. 

The branches of the abdominal aorta are twenty in number. 
The following table shows the order in which these branches are 
given off and also the branches of distribution of each. 



THE ABDOMINAL AORTA. 



403 



A TABLE OF THE BRANCHES OF THE ABDOMINAL 

AORTA. 



ABDOMINAL 

AORTA. 
(9 branches.) 



r Inferior phre- 
nic 



COELIAC AXIS. 



( Thoracic. 
( External branches -j Capsular (to supra-renal 
(2 \ ] ( capsule). 

v ' \ Internal branches. 

' Gastric (coronaria ventriculi). 

{ Pyloric. f Gastro epiploica 

tt .. .' Gastro duode- J dextra. 

P '' 1 nalis. j Superior pancre- 

(^ Cystic, [atico-duodenalis 

f Pancreaticse parvse. 



Superior 
teric. 



mesen- 



SUPRA-RENAL. 



1 • Pancreatica magna. 

LSplenic....j Vasabrevia! 

(^Gastro-epiploica sinistra. 

Inferior pancreatico-duodenalis. 
Vasa intestini tenuis (10 or 12). 
T1 r j Ascending branch. 

lleo-colic. -j Descendin g branch. 

„ .. , ( Ascending branch 

Cohca dextra. -j Descend > g branch. 

Colica media. 
W I Left. 



Renal or emulgent. . . (2) j L ^ 

sp ERMATI c. w j **$£» ; ;;••;;;; ; fed*, sinistra. | £— ?*. 

Inferior mesenteric -{ Sigmoid. 



Lumbar. 
Sacra-media. 



(8) j 



Abdominal branches. 
Dorsal branches. . . . 



Superior hemorrhoidal. 



These twenty branches may be arranged on a basts of their dis- 
tribution in three sets, as follows : 



Phrenics (2). 
I. To parietes of abdomen. . (n branches) ^ Lumbar (8). 

Middle sacral (1). 

!Coeliac axis. 
Superior mesenteric. 
Inferior mesenteric. 



III. To genito-urinary organs , 



( Supra-renal (2). 
(6 branches) -j Renal (2). 

( Spermatic (2). 



Total, 20 branches. 

The inferior phrenic branches of the abdominal aorta are two 
in number and are distributed to the diaphragm, the sides of the 
thorax and the suprarenal capsule. 

The CCELIAC AXIS springs from the aorta between the two 
crura of the diaphragm. It gives off three principal branches 
viz., the gastric, the hepatic and the splenic. 



404 ANGIOLOGY. 

The gastric branch supplies the lesser curvature of the stomach. 

It is often called coronaria ventriculi. 
The hepatic branch gives off three specially-named arterial 
trunks, viz., the pyloric, the gastro-duodenalis, and the 
cystic. 
The pyloric branch supplies the pyloric end of the 

stomach. 
The gastro-duodenalis branch of the hepatic, by dividing 
into two branches, whose names can be found by re- 
ferring to the table of the branches of the abdominal 
aorta, supplies the greater curvature of the stomach 
and a portion of the duodenum. 
The cystic branch of the hepatic supplies the gall 

bladder and the liver. 
The hepatic artery bears important relations, at the 
transverse fissure of the liver with the hepatic duct 
and the portal vein. It will be found described more 
in detail in the description of that organ. 
The splenic artery, by its four branches whose names are given 
in the table of the branches of the aorta, supplies the 
pancreas and the splenic end and greater curvature 
of the stomach ; although its main distribution, as its 
name indicates, is to the spleen. 
The superior mesenteric artery arises from the front of 
the aorta behind the pancreas, between which and the duodenum, 
it passes to be distributed between the layers of the mesentery. 
Its five branches, mentioned in the table of the branches of the 
abdominal aorta, are distributed to the various portions of the 
mesentery and to the whole length of the small intestine, ex- 
cepting the upper part of the duodenum. It also supplies the 
caecum and the ascending and transverse portions of the colon. 
This artery assists in forming, by its colica dextra and colica 
media branches, the largest anastomosis in the human body. 

The suprarenal branch of the aorta is distributed to the supra- 
renal capsula. 

The renal branches of the aorta are two in number and are 
distributed to the kidneys, the ureter, and the suprarenal cap- 
sule. 

The spermatic branches of the aorta are the longest arteries 
in the body, and, after passing through the inguinal canal, are 
distributed to the testicle of either side, in the male ; and, in the 
female, to the ovaries of either side, the round ligament, and the 
labia. 



ARTERIES OF THE PELVIS. 



405 



The inferior mesenteric artery arises from the left side of 
the aorta, about two inches above bifurcation. Its three branches 
are distributed to the descending and sigmoid flexure, of the colon 
and the rectum. 

The lumbar arteries are four in number upon either side, and 
arise from the back part of the abdominal aorta. They are dis- 
tributed to the parietes of the abdominal cavity. 

The middle sacral artery arises from the abdominal aorta, at 
its point of bifurcation, and passes, down into the pelvis, upon the 
middle of the sacrum. It affords a point of anastomosis, in case 
of ligature of the common iliacs, with the lateral sacral arteries. 

COLLATERAL CIRCULATION. 

The collateral circulation, in case the abdominal aorta be tied, varies with the sit- 
uation of the ligature. It is chiefly performed however by the anastomoses between 
the following vessels. 
Internal mammary (branch of subclavian) with the deep epigastric (a branch of external 

iliac). 
Lumbar arteries (branches of aorta) with Mo-lumbar (branch of internal iliac). 
Branches of the superior mesenteric with branches of the inferior ??iesenleric. 
Branches of inferior mesenteric with branches of the internal pudic . 



ARTERIES OF THE PELVIS. 

The arteries of the pelvis, as enumerated in the following 
table, are derived from the trunks of the two common iliac arter- 
ies, which are the branches of bifurcation of the abdominal aorta. 



A TABLE OF THE ARTERIES OF THE PELVIS. 

External iliac, j Deep epigastric 



COMMON 

ILIAC 
ARTERY. 



(2 branches.) J Circumflex iHac< 



\ Pubic. 



Internal iliac. 
(12 branches.) 



f Superior vesical. 
Middle vesical. 
Inferior vesical. 
Middle hemorrhoidal. 
'Anterior trunk (9) \ Uterine. 
Vaginal. 
Obturator. 
Sciatic. 
Pudic. 

( Ilio-lumbar. 

I Lateral sacral. 

\ Gluteal. < s «Perncial. 



Posterior trunk (3) 



Total, 12 



\ Deep. 



406 ANGIOLOGY. 



COMMON ILIAC ARTERY. 

This artery, upon either side of the body, extends downwards 
and outwards, from the bifurcation of the aorta, at the left side 
of the 4th lumbar vertebra, to opposite the sacro-ihac synchondro- 
sis, where it bifurcates into the external and internal iliac arteries. 
The right common iliac artery is slightly longer than the left, 
since the aorta lies upon the left side of the vertebral column. 

The common iliac artery possesses different relations upon 
the right and the left side of the body, as will appear in the plan 
of relations pertaining to each. 

PLAN OF RELATIONS OF RIGHT COMMON ILIAC ARTERY. 

In front. 
Peritoneum. 
Small intestines. 
Sympathetic nerves. 
Ureter. 



Outer side. 
Vena cava. 

Right common iliac vein. 
Psoas muscle. 



Behind. 
Right and left common iliac veins. 

PLAN OF RELATIONS OF LEFT COMMON ILIAC ARTERY. 

In frmt. 
Peritoneum. 
Sympathetic nerves. 
Rectum. 

Superior hemorrhoidal artery. 
Ureter. 



Inner side. / \ Outer side. 

Left common iliac vein. I aC r ery ' / Psoas muscle. 



Behind, 
Iliac vein. 

Collateral Circulation. 

The principal agents in carrying on the collateral circulation 
after the application of a ligature to the common iliac, are, 





EX TERNAL ILIA C AR TER Y. 



407 



1. The anastomoses of the hemorrhoidal branches of the in- 
ternal iliac with the superior hemorrhoidal branch of the inferior 
mesenteric. 

2. The anastomoses of the uterine and ovarian arteries, and 
of the vesical arteries of opposite sides. 

3. The lateral sacral with the middle sacral artery ; 

4. The epigastric artery with the internal mammary, inferior 
intercostal and lumbar arteries ; 

5. The ilio-lumbar with the last lumbar artery. 

6. The obturator artery, by means of its pubic branch, with 
the vessel of the opposite side, and with the internal epigastric. 

7. The gluteal with the posterior branches of the sacral ar- 
teries. 

EXTERNAL ILIAC ARTERY. 

This artery extends from the bifurcation of the common iliac 
artery, opposite to the sacro-iliac synchondrosis, to beneath Pou- 
parfs ligament midway between the anterior superior spine of 
the ilium and the symphysis pubis, where it becomes the femoral 
artery. 

In adult life, the external iliac artery is somewhat larger than 
the internal iliac, although, in the foetus, it is usually much 
smaller. It has the following relations within the pelvis. 

PLAN OF RELATIONS OF EXTERNAL ILIAC ARTERY. 

In front. 
Peritoneum, intestines, and iliac fascia. 

^ ( Spermatic vessels. 

T, ., ) Genito-crural nerve. 

Pouparts j Circumflex iliac vein. 

Ligament, y Lyrn p hatic vessels and g i an d s . 



Outer side. ["Eyftemzl Iliac \ Inner side. 

Psoas magnus. I Artery. i External iliac vein and vas 

Iliac fascia, \ / deferens (at femoral arch.) 



Behind. 
External iliac vein. 

Branches. 

This artery gives off, in its course, two branches called the 
epigastric and the circumflex iliac arteries. 

The epigastric artery is larger than its accompanying branch, 
and arises near to Poupart's ligament, from the front of the ex- 




408 



ANGIOLOGY. 



ternal iliac artery. As it descends obliquely upwards and in- 
wards in the subperitoneal areolar tissue, it passes behind the 
inguinal canal and to the inner side of the internal abdominal 
ring, and encircles the vas deferens in the male, and, in the female, 
the round ligament. It then ascends behind the sheath of the 
rectus muscle and, at its termination anastomoses with the supe- 
rior epigastric branch of the internal mammary artery. The union 
of these two vessels establishes the longest anastomosis in the 
human body. 

The epigastric artery gives off two branches as follows : 

1. A cremasteric branch, which descends upon the 
spermatic cord, and supplies the cremaster muscle. 

2. The pubic branch, which descends behind the 
pubes, on the inner side of the femoral ring, and 
which anastomoses with the obturator artery. 

The circumflex iliac artery arises near Poupart's ligament, 
and runs upwards and outwards, along the inner lip of the crest 
of the ilium, to join with the gluteal artery. 

Collateral Circulation. 

The principal anastomoses in carrying on the collateral circu- 
lation, after the application of a ligature to the external iliac, are, 

(i) The ilio-lumbar with the circumflex iliac. 

(2) The gluteal with the external circumflex. 

(3) The obturator, with the internal circumflex, 

(4) The sciatic with the profunda femoris. 

(5) The ititemal pudic with the external pudic, and with the 
internal circumflex. 

When the obturator artery arises from the epigastric, the ex- 
ternal iliac is supplied with blood by branches, either from the 
internal iliac, the lateral sacral, or from the internal pudic. The 
epigastric branch receives its supply after the external iliac is tied 
from the internal mammary and inferior intercostal arteries, and 
from the internal iliac, by the anastomoses of its branches with 
the obturator. 

INTERNAL ILIAC ARTERY. 

The internal iliac artery, one of the branches of bifurcation of 
the common iliac, is a short trunk, which extends from the sacro- 
iliac synchondrosis to the upper border of the great sacro-sciatic 
foramen, where it divides into an anterior and a posterior trunk. 
Its length is usually about one and a half inches. 



INTERNAL ILIAC ARTERY. 



409 




PLAN OF THE RELATIONS OF THE INTERNAL ILIAC ARTERY. 

In front. 
Peritoneum. 
Ureter. 



Outer side. 
Psoas magnus. 



Behind. 
Internal iliac vein. 
Lumbo-sacral nerve. 
Pyriformis muscle. 

Branches. 

The internal iliac artery, through its two divisions, gives off 
twelve branches. These branches have been also divided into 
two sets, termed the visceral and the non-visceral branches. The 
former set include the first six branches arising from the anterior 
trunk, and, in addition, a hemorrhoidal branch of the pudic ar- 
tery ; while the latter comprise the remaining branches of the 
internal iliac artery. 

The branches given off from the internal iliac artery may be 
again arranged, on a basis of their distribution, in three distinct 
sets as follows : 

f Obturator. 

I. Those which pass out of the pelvis (4) \ s^ifor ischiatic. 

[ Internal pudic. 

II. Those distributed to the walls of the pelvic j Lateral sacral, 
cavity (2) \ Ilio-lumbar. 

["Vesical arterius (3). 

ttt tu j- * -a * j 4. ± 7 • /a\ J Middle hemorrhoidal. 

III. 1 hose distributed to pelvic viscera ('1 Ut i ( 

Total, -^>> femaIe0nly - 

The vesical branches are usually three in number, and are dis- 
tributed to the bladder, the prostate gland, and the vesiculae 
seminales. From the superior vesical branch, a twig is given off 
called the artery of the vas deferens. 

The middle hemorrhoidal branch joins with the superior he- 
morrhoidal branch of the inferior mesenteric, and with the infe- 
rior hemorrhoidal branch of the internal pudic artery. 

The uterine branches, distributed in the folds of the broad 
ligament, supply the neck and body of the uterus. 

The vaginal branch descends upon the vagina to the neck of 
the bladder and the rectum. 



4io 



ANGIOLOGY. 



The OBTURATOR ARTERY usually arises from the anterior 
trunk of the internal iliac artery. It has frequent abnormalities 
of origin, however, which are of great surgical importance, since 
in some cases the operation for strangulated femoral hernia is 
complicated by an inevitable wounding of this artery. In one, 
out of three a?id a half cases, it arises as a branch of the epigastric 
artery ; in one out of seventy-two cases, it arises both from the in- 
ternal iliac and the epigastric arteries ; while occasionally it arises 
from the external iliac artery. It is said to arise from the epigas- 
tric more frequently in females than in males. 

This artery passes through the obturator foramen, and subse- 
quently sends an articular branch to the hip-joint, which enters 
the joint through the cotyloid notch. It anastomoses with the 
circumflex and sciatic arteries. 

The SCIATIC ARTERY is the largest of the two terminal 
branches of the anterior trunk of the internal iliac artery. It 
passes through the great sacro-sciatic foramen, below the pyrifor- 
mis muscle, and between the great sciatic nerve and the pudic 
vessels and nerve. It gives off the following branches. 

Muscular. Coccygeal. Inferior gluteal. 

Articular (to hip joint). Comes nervi ischiadici. 

The PUDIC ARTERY is the smallest of the two terminal branches 
of the anterior division of the internal iliac artery. It descends 
in front of the pyriformis muscle and the sacral plexus of nerves, 
till it reaches the great sacro-sciatic foramen, through which it 
escapes in company with the pudic nerve. It then winds around 
the spine of the ischium and again enters the pelvis, in company 
with the pudic nerve, through the lesser sacro-sciatic foramen. 

The guide to the pudic artery, as it passes over the spine of 
the ischium, consists of a line drawn from the posterior supe- 
rior spine of the ilium to the outer side of the tuberosity of the 
ischium ; the junction of the middle and the lower thirds of this 
line will be found to lie directly over this artery. 

The pudic artery gives off six branches in the vicinity of the 
perineum, as follows : 

f Inferior hemorrhoidal. 

Superficial perineal. 

Transverse perineal. 

Artery of the bulb. 

Artery of the corpora cavernosa. 
__ Dorsal artery of the penis. 

The inferior he7norrhoidal branches supply the lower 
part of the rectum and the anus, having previously 
crossed the ischio-rectal fossa. 



Pudic Artery. 
(6 branches.) 



BRANCHES OF THE INTERNAL ILIAC ARTERY. 41 J 

The superficial perineal branch supplies the integu- 
ment of the scrotum and labia. 

The artery of the bulb supplies Cowper's glands and 
the bulb of the corpus spongiosum. 

The dorsal artery of the penis penetrates to the sus- 
pensory ligament and supplies the integument, glans 
penis, and prepuce. 
The ILIO-LUMBAR ARTERY arises from the posterior division 
of the internal iliac artery. It supplies the muscles of the lumbar 
and iliac regions. 

The LATERAL SACRAL ARTERIES are usually two in number. 
They supply, through the anterior sacral foramina, the contents 
of the spinal canal ; and, after escaping through the posterior sac- 
ral foramina, the skin and muscles on the back of the sacrum. 

The GLUTEAL ARTERY is the largest branch of the internal iliac 
artery, and is a direct continuation of its posterior trunk. It 
passes through the great sacro-sciatic foramen above the pyrifor- 
mis muscle and supplies, by its superficial and deep branch, the 
glutei muscles and the integument over the sacrum. 

The surgical guide to the gluteal artery, at its point of escape, 
consists of a line drawn from the posterior superior spine of the 
ilium to the upper border of the great trochanter of the femur, 
when that bone is rotated inwards ; the junction of the upper and 
the middle thirds of this line will be found to lie over this artery, 
as it emerges from the sciatic notch. 

Collateral Circulation. 

The principal agents in carrying on the circulation in the parts 
supplied by the internal iliac, after that artery be tied, would be 

(1) The anastomosis of the uterine and ovarian arteries. 

(2) The anastomosis between opposite vesical arteries. 

(3) The hemorrhoidal brandies of the internal iliac with those 
from the inferior mese?tteric. 

(4) The obturator artery, by means of its pubic branch, with 
the vessel of the opposite side, and with the epigastric and inter- 
nal circumflex. 

(5) The circumflex and perforating branches of the femoral, 
with the sciatic. 

(6) The gluteal with the posterior brandies of the sacral ar- 
teries. 

(7) The ilio-lumbar with the last lumbar. 

(8) The lateral sacral with the middle sacral. 

(9) The circumflex iliac with the ilio-lumdar and gluteal. 



412 



ANGIOLOGY. 



ARTERIES OF THE LOWER EXTREMITY. 

The arteries of the lower extremity are principally derived 
from the femoral artery, although some of the branches of the 
internal iliac are distributed to the gluteal region of the hip. 

FEMORAL ARTERY. 

This artery commences beneath Pouparfs ligament, being a 
direct continuation of the external iliac, and, passing down the 
front and the inner side of the thigh, terminates at the junction 
of the middle and lower third of the thigh, at an opening in the 
lower part of the adductor magnus muscle. It here becomes 
the popliteal artery. 

This artery is, at first, contained in a space called Scarpa's tri- 
angle ; and, in the middle third of the thigh, in a canal, called 
Hunters canal, between the vastus internus and the tendons of 
the adductor longus and the adductor magnus muscles. 

The following table illustrates the branches of the femoral 
artery. 

A Table of the Branches of the Femoral Artery. 

f Superficial epigastric. 





Superficial circumflex iliac. 






Superficial external pudic. 






Deep external pudic. 


Ascending. 






' External circumflex. 


Descending. 


femoral artery. 






Transverse. 


(7 branches.) 






Ascending. 






Internal circumflex. . 


Descending. 




Profunda _ 




Articular. 




FEMORIS. 




Superior. 






Perforating 


Middle. 
Inferior. 




Muscular branches. 






^Anastomot 


[CA MAGNA 


Superficial branch 
! Deep branch. 



Scarpa's space. 
Scarpa's triangle is bounded as follows: Above, by Poupart's 
ligament; internally, by the adductor longus muscle/ externally, 
by the sartorius muscle. The floor of this space is formed, from 
without inwards, by the iliacus, psoas, pectineus, adductor longus, 
and a part of the adductor brevis muscles. This triangle con- 
tains, I. The femoral artery, which runs from its base to its apex ; 
2. The femoral vein, which, at the upper part of the triangle, 



FEMORAL ARTERY. 



413 



lies upon the inner side of the artery, but, lower down, upon the 
posterior aspect of the vessel ; 3. The anterior crural and long 
saphenous nerves, which lie upon the outer side of the artery ; 
and 4. The internal cutaneous nerve and branches of the genito- 
crural nerve which lie in front of the artery. 

The sartorius muscle is the main guide to the femoral artery, 
and can be made prominent underneath the integument by in- 
sructing the patient to raise the leg. 

The direction of the femoral artery can be denned upon the 
surface of the body by drawing a line from the centre of Poupart's 
ligament to the tubercle on the inner side of the femur near to 
the knee, to which the fibres of the adductor magnus muscle are 
attached. 

The femoral artery lies beneath this line for the upper two- 
thirds of its extent. 

Compression of the femoral artery high up in its course should 
be made immediately below Poupart's ligament and in a direction 
upwards and backwards, so as to impinge the artery against the 
pubes. 

Compression of the femoral artery, may also be made near to 
the apex of Scarpa's triangle, and the pressure should, in this case, 
be directed outwards so as to crowd the artery against the shaft 
of the femur. 

The incision for ligature of the femoral artery in Scarpa's tri- 
angle should commence about a hand's breadth below Poupart's 
ligament and should be continued in a line of the artery for about 
three inches. By this incision the profunda femoris is avoided 
and the artery is tied below its branches. 

Branches. 

The superficial epigastric branch passes through the saphenous 
opening and then upwards and inwards, in the superficial fascia of 
the abdomen. 

The superficial circumflex iliac branch pierces the fascia lata 
and is distributed to the crest of the ilium. 

The superficial external pudic branch passes through the saphe- 
nous openingand crosses the spermatic cord or the round ligament 
to reach its point of distribution, in the integument of the abdo- 
men, scrotum, and labia. 

The PROFUNDA FEMORIS branch or deep femoral artery is by 
some authors described as a branch of bifurcation of the femoral 
artery. It arises from the outer and back part of the femoral 
artery, one or two inches below Poupart's ligament ; and nearly 
equals, in point of size, the superficial part of the femoral artery. 



414 



ANGIOLOGY. 



PLAN OF THE RELATIONS OF THE PROFUNDA ARTERY. 



In front. 
Femoral and profunda veins. 
Adductor longus. 




Outer side. 
Vastus internus. 



Behind. 
Iliacus. 

Adductor brevis. 
Adductor magnus. 

The branches of the profunda femoris artery are divided into 
three sets called respectively the external circumflex, the internal 
circumflex, and the perforating branches. 

The external circumflex artery divides into an ascending, de- 
scending, and transverse branch. These three branches supply 
anastomotic branches to the knee, and the muscles on the outer 
aspect of the thigh. 

The internal circumflex artery also divides into an ascending, 
descending, and articular branch. These three branches supply 
the muscles on the inner aspect of the thigh and the hip-joint. 

The perforating arteries are usually three in number and are 
called the superior, middle, and inferior perforating arteries. They 
supply the muscles at the back part of the thigh. The inferior 
perforating artery also gives off the nutrient branch of the femur. 

All the branches of the profunda femoris artery anastomose 
freely with each other as well as with the vessels of the gluteal 
region and some of the branches of the popliteal artery. 

The MUSCULAR BRANCHES of the femoral artery are numerous, 
and are given off along the entire course of the vessel. 

The ANASTOMOTICA MAGNA arises from the femoral artery in 
Hunter's canal. Its superficial branch accompanies the internal 
saphenous nerve to the integument of the inner side of the knee ; 
while its deep branch anastomoses with other arteries in front 
of the knee. 



POPLITEAL ARTERY. 



Collateral Circulation. 



4i5 



After ligation of the femoral artery, the three following vessels % 
maintain the circulation of the limb, by anastomotic channels, 
formed as indicated below. 

( Gluteal. 
External circumflex, with 3 arteries. •< Iliolumbar. 

( Circumflex iliac. 

Internal circumflex, with 2 arteries. -J ggjjj™ ° r " 

Perforating arteries, with 1 artery Comes nervi ischiadici. 

POPLITEAL ARTERY. 

This artery commences at an opening in the lower part of the 
adductor magnus muscle, and, passing downwards and outwards 
to the back of the knee joint and then vertically downwards It 
terminates at the lower border of the popliteal muscle, where it di- 
vides into the anterior and posterior tibial arteries. 

Popliteal space. 

This artery is contained in a lozenge-shaped space called the 
popliteal space, with the following boundaries. 

Internally. The semimembranosus muscle, the inner head of 
gastrocnemius muscle, and the inner condyle of the 
femur. 
Externally. The biceps muscle, the outer head of gastrocne- 
mius muscle, the plantaris muscle, and the outer con- 
dyle of the femur. 
The floor of this space is formed by the posterior surface of 
the femur, the posterior ligament of the knee joint, 
the popliteus muscle, and the upper part of the tibia. 
This space contains the popliteal artery, popliteal vein, the 
internal popliteal nerve, the external popliteal nerve, the small 
sciatic nerve, the articular branch of the obturator nerve, the ex- 
ternal saphenous vein, and lymphatic glands and adipose tissue. 

The relations of the important parts contained within this 
space are as follows. 

The popliteal artery lies nearest to the floor. 

The popliteal vein lies superficial to the artery and slightly 

external to it. 
The internal popliteal nerve lies superficial to the vein and 

slightly external to it. 
The external popliteal nerve lies close to the tendon of the 
biceps muscle. 



4 l6 ANGIOLOGY. 

The popliteal artery bifurcates into the anterior and posterior 
tibial arteries, at a point situated one inch below the level of the 
tubercle of the tibia ; and the peroneal artery is given off two 
inches below the tubercle. If amputation be performed, there- 
fore, one inch below the level of the knee joint, only 07ie large 
artery will require a ligature ; if two inches below the knee, two 
large arteries will require a ligature, viz., the anterior and pos- 
terior tibials ; if three inches below the knee, three large arteries 
will require a ligature, viz., the two tibials and the peroneal. 

Branches. 

The following table enumerates the seven branches of the 
popliteal artery, which are given off within the popliteal space. 



POPLITEAL ARTERY. 
(7 branches.) 



Superior external articular. 
Superior internal articular. 
Inferior external articular. 
Inferior internal articular. 
Azygos articular. 

Muscular branches.. ■] T f ■ , 

( Inferior or sural. 

^ Cutaneous. 



The muscular branches are distributed, above, to the hamstring 
and vasti muscles ; and, below, to the gastrocmenius and plantaris 
muscles. 

The cutaneous branches supply the integument of the back 
part of the leg. 

The superior articular branches supply the femur, the knee- 
joint, and the vasti muscles. 

The azygos articular branches pierce the posterior ligament 
of the knee-joint and supply its internal structures. 

The inferior articular branches, which pass beneath the lat- 
eral ligament of the knee-joint upon either side, form an arterial 
anastomosis in front of the knee. 

ANTERIOR TIBIAL ARTERY. 

This artery arises at the bifurcation of the popliteal artery, at 
the lower border of the popliteus muscle, and, passing between the 
two heads of the tibialis posticus muscle and through an opening 
in the interosseous membrane, extends down the front of the leg 
to the ankle-joint, where it becomes the dorsalis pedis artery. 

The anterior tibial nerve is, at first external, then anterior, and 
then external to this artery, in its course down the leg. 

This artery has two vence comites, which lie upon either side 
of it. 

The anterior tibial artery corresponds in its direction with the 



D OR SALIS PEDIS A R TER V. 4 1 7 

outer border of the tibialis anticus muscle, and, if this muscle be 
put in action, a guide to the incision necessary to ligate this ves- 
sel will be afforded. 

Branches. 

The anterior tibial gives off three branches as follows. 

f Recurrent tibial, 
Anterior Tibial Artery. J Muscular branches. 

(3 branches.) j Malleolar. . j ^^ 

The recurrent tibial branch is distributed to the front of the 
knee. 

The muscular branches supply the muscles upon either side 
of the artery. 

The malleolar branches are two in number and pass beneath 
the tendons at the inner and outer sides of the ankle, to anasto- 
mose with, the posterior tibial, the internal plantar, the peroneal 
and the tarsal arteries. 

DORSALIS PEDIS ARTERY. 

This artery extends, as a continuation of the anterior tibial, 
from the bend of the ankle, along the tibial side of the foot, to 
the back part of the first interosseous space, where it divides into 
two branches, viz., the dorsalis hallucis and the communicating. 

This artery has the anterior tibial nerve on its outer side. 

The course of dorsalis pedis artery may be described upon the 
surface of the dorsum of the foot by a line drawn from the cen- 
tral point in front of the ankle, to the space between the 1st and 
2d metatarsal bone. 

Branches. 

The dorsalis pedis artery gives off five branches as follows. 

f Tarsal. 

_ I Metatarsal. \ 3rd, 4th and 5th interosseous. 

Dorsalis Pedis Artery. I _ . ' , . 

(5 branches,) 1 Dorsal arter y of S ieat toe ( Ist interosseous). 

Communicating. 
(_ Interosseous. 

The tarsal branches anastomose with the metatarsal, external 
malleolar and external plantar arteries. 

The metatarsal branch gives off the three outer dorsal inteross- 
eous arteries, which are joined by the anterior and posterior per- 
forating arteries, and which supply digital branches to the dorsum 
of three and a half toes on the outer side of the foot. 

The dorsal artery of the great toe corresponds to a first dor- 



4i8 



ANGIOLOGY. 



sal interosseous artery, and supplies digital branches to the 
dorsum of one and a half toes on the inner side of the foot. 

The communicating branch dips downwards between the two 
heads of the first dorsal interosseous muscle, and, by joining with 
the external plantar artery completes the pla?itar arch. It also 
gives off, on the sole of the foot, digital branches to one and a 
half toes on the inner side of the foot. 

POSTERIOR TIBIAL ARTERY. 



This artery arises, as a branch of bifurcation of the popliteal 
artery, at the lower border of the popliteus muscle. It divides in 
the vicinity of the internal malleolus, into the two plantar arte- 
ries. The most frequent point of division into the plantar arte- 
ries may be described by a line drawn from the tip of the internal 
malleolus to the middle of the convexity of the heel, which will 
intersect the artery at its point of bifurcation ; and any variations 
from this point are usually below rather than above the level of 
this line. 

The internal popliteal nerve is, at first, posterior and internal 
to the artery, but it soon crosses to its outer side. 

The direction of the posterior tibial artery may be indicated 
by a line drawn from the central point of the upper part of the 
calf to a point behind the ankle and one half inch posterior to 
the tibia, where the artery can often be felt to pulsate. 

Branches. 

The posterior tibial artery gives off seven branches, including 
its two terminal trunks, as is shown in the following table. 

f Muscular. 

■r. •, j Nutrient to fibula. 

reroneal. < n ■ J ■ .., . ,. u . •■ 

Communicating with post tibial. 

[Anterior peroneal. 

Muscular branches. 

Nutrient to tibia. 

Communicating to peroneal. 

Internal calcanean. 

Internal plantar. 



Posterior Tibial Artery. 
(7 branches.) 



External plantar. 



Terminal branches. 



The PERONEAL branch is given off about one inch below the 
lower border of the popliteus muscle, and it extends to the outer 
side of the os-calcis, where it joins with the external malleolar and 
the external plantar arteries. It supplies the soleus, the three pe- 
ronei, and the muscles of the deep layer of the leg. It also gives 
off a nutrie?it artery to the fibula, a communicating branch to the 
posterior tibial artery, and a large branch, called the anterior 



THE PLANTAR ARTERIES. 



419 



perineal artery, which anastomoses, at the outer side of the tar- 
sus, with the external malleolar and tarsal arteries. 

The muscular branches of the posterior tibial artery are dis- 
tributed to the soleus and the deep layer of muscles. 

The nutrient artery of the tibia is very large and runs towards 
the ankle. 

The internal calcanean branches supply the integument about 
the heel and the fat about the tendo Achillis. They are also dis- 
tributed to the muscles on the inner side of the sole of the foot. 
They are occasionally derived from the external plantar artery. 

PLANTAR ARTERIES. 

The plantar arteries are branches of bifurcation of the poste- 
rior tibial vessel. 

The INTERNAL PLANTAR artery is the smallest of the two, and 
ends, at the extremity of the first metacarpal bone, in a small branch 
which runs along the inner border at the great toe. 

The EXTERNAL PLANTAR artery passes at first outwards, and 
then forwards, upon the sole of the foot, as far as the base of the 
5th metatarsal bone. It then turns obliquely inwards to the in- 
terval between the bases of the 1st and 2d metatarsal bone, where 
it joins with the communicating branch from the dorsalis* pedis 
artery, and thus completes the plantar arch. 

The first portion of the course of the external plantar artery 
may be described, upon the sole of the foot, by a line drawn 
from the hollow behind the inner malleolus to the base of the 5th 
metatarsal bone ; but, from this point, its course runs transversely 
across the sole of the foot, where it lies in relation with the bases 
of the metatarsal bones. 

Branches. 

The external plantar artery gives off two sets of branches, 
which comprise ten vessels as shown in the following table. 

External Plantar ( 3 Posterior -perforating. 

(2 sets of branches.) \ 7 Digital. . \ P ! f *« interosseous branches. 
v ' ( ' 6 (3 anterior perforating. 

Total, 10 

The posterior perforating branches pass through the back part 
of the three outer interosseous spaces, and anastomose with the 
dorsal interosseous branches of the metatarsal artery. 

The digital branches are divided into two sets, as is shown in 
the table above. 



4 2 ANGIOLOGY. 

The plantar interosseous arteries supply digital branches to 
the plantar surface of three and a half toes on the 
outer side of the foot. 

The anterior perforating arteries pass through the front part 
of the outer three interosseous spaces, and, like the pos- 
terior perforating, join with the dorsal interosseous 
branches of the metatarsal artery. 

THE VEINS OF THE BODY. 

The system of veins which accompany the arteries of the 
various portions of the body, are in many instances giv^i the 
same name as the artery which they accompany, thus rendering 
a separate description of them unnecessary ; while, with others, 
their points of origin are too irregular to admit of any positive 
statements concerning them. Certain venous trunks possess a 
greater importance than others, since either from their situa- 
tion, their tributaries, or their relation to other parts, they are 
associated with points of practical interest and value. 

Some veins unlike the arteries contain valves in their interior, 
which consist of pouches adherent to their walls, and which tend, 
when present, to prevent the backward flow of blood, when the 
circulation is in opposition to gravity. We therefore fail to 
find them in the larger venous trunks, where the circulation 
if in opposition to gravity, is assisted greatly by the vacuum 
created within the thorax during the act of inspiration ; and 
in certain veins, where the current of blood is accelerated by 
gravity, as in the neck, Nature, no longer requiring these valves 
as a protective measure, has omitted them either entirely or in 
part. 

Veins admit of a three-fold division, viz., into superficial veins, 
deep veins, and sinuses. 

The superficial veins return the blood from the integument and 
the superficial structures of the body, and take their course, as a 
rule, between the layers of superficial fascia, until they reach con^ 
venient situations for their termination in the deep veins. Since 
they are usually unaccompanied by arteries, they are the ones 
selected as a rule, for venesection. 

The deep veins are usually enclosed, in the limbs, in the 
sheath of some large artery which they accompany ; but, if the 
accompanying artery be of secondary calibre, these deep veins 
are usually placed upon either side of the artery and are termed 
vence comites. 



THE VEINS IN GENERAL. 42 1 

Sinuses differ from veins in their structure and mode of distri- 
bution and are confined to special organs, within whose substance 
or their investing coverings they are usually situated. 

Veins communicate with each other more frequently than 
arteries, both in the larger and the smaller trunks ; thus the venaz 
comites constantly communicate, in their course, by transverse 
branches, which cross the artery; and the various venous plexuses 
of the body afford another striking example of the tendency 
of veins towards frequent anastomosis. This tendency to fre- 
quent communication has been explained, as an effort on the 
part of nature to obviate the obstructions to which the veins are 
particularly liable, from the thinness of their coats ; and also on 
account of their inability to overcome any impediment, from 
the weak force of their current. 

The veins, like the arteries, have walls composed of three dis- 
tinct coats. 

The internal coat resembles that of the arteries and is serous 
in character. 

The middle coat has less muscular fibre in its structure than 
exists in the arteries ; and is also much thinner than in arteries 
of corresponding calibre. 

The external coat is composed chiefly of connective tissue and 
longitudinal elastic fibres. 

In the large veins connected with the heart, viz., the venae 
cavae and the four pulmonary veins, the muscular fibres of that 
organ are continued for some distance in their walls. 

The circulation within the venous system is due partly to the 
pressure transmitted from the arteries ; partly to muscular pressure 
aided by the valves ; partly to gravity, especially in the veins of 
the head, neck and thorax ; and partly to the suction created by 
the vacuum formed within the pleural and pericardial sacs during 
inspiration. 



422 



ANGIOLOGY. 



TABLE OF THE CHIEF VEINS OF THE HEAD AND 

NECK. 



f Superior longitudinal sinus. 
| Inferior longitudinal sinus. 
| Straight sinus. 
f i. Lateral sinus. -| Occipital sinuses. 
[ Ophthalmic vein. 
I Superior petrosal sinus, 
[inferior petrosal sinus. 

Ascending j Meningeal veins, 
pharyngeal. \ Pharyngeal veins. 

Superficial dorsal. 

Lingual -( Lingual. 

Ranine. 



Internal jugu- 
lar vein. 



THE INNO 
MIN ATE 
VEIN is^ 
formed by the 
union of | 






Facial. 



Angular 



Inferior palpebral. 

Dorsal and lateral. 
Nasal veins. 



Anterior internal 

maxillary 



["Supraorbital. 
J Frontal. 
) Palpebral. 
[Nasal. 



f Alveolar branches. 

Infraorbital, 
■j Descending palatine. 
I Naso-palatine. 
[Vidian. 



Coronary i Superior 



Inferior 



5. Occipital.... -j 



Buccal. 
Masseteric. 
Labial. 
Submental. 
Inferior palatine. 
Tonsillar. 
1. Glandular. 

Mastoid vein. 
Cervical. 



6. Superior ( Thyroid. 

thyroid, j Laryngeal. 

L 7. Middle thyroid. 



Subclavian 

vein. 



Vertebral. 



Spinal. 

Deep cervical. 

Ascending cervical. 



fi. Internal maxillary. 



2. External jug- 
ular. 



Anterior jug- 
ular. 



f Middle meningeal. 

Inferior dental. 

Deep temporal. 

Pterygoid. 
[Masseteric. 

f Anterior. 
Posterior. 

T<-poral j g£!B!"-»"* 

I Anterior auricular. 
[Transverse facial. 



auricu- j Auricular. 

j Stylo-mastoid. 



Posterior 
lar. 



Branch to the internal jugular, 
Supra-scapular 



Supra-spinal. 
Infra-spinal. 



Transverse cervi- j Superficial cervical, 
cal. "J Posterior scapular. 



VEINS OF THE DURA MATER. 423 



SINUSES OF THE DURA MATER. 

The sinuses of the skull are channels, formed by the dura 
rnater, for the transmission of blood, although their inner coat 
is formed by a continuation of the inner or serous coat of the 
veins. They are fifteen in number and may be divided as fol- 
lows : 

f Superior longitudinal sinus. 

I Inferior longitudinal sinus. 
Single Sinuses (5)^ Straight sinus. 

I Circular sinus. 

I Transverse sinus. 



Pairs of Sinuses (5) 



Occipital sinuses. 
Lateral sinuses. 
Cavernous sinuses. 
Superior petrosal sinuses. 
! Inferior petrosal sinuses. 



The superior longitudinal sinus commences at the foramen 
ccecum, through which it frequently communicates with the 
veins of the nose and with a vein from the frontal sinus, and runs 
backwards along the upper margin of the falx cerebri, till it 
reaches the torcular Herophili. It receives the superficial veins 
of the convexity of the hemispheres, and veins from the diplce 
and the dura mater ; and also the parietal veins from the pericra- 
nium, at the posterior extremity of the sagittal suture. 

The situation of the superior and inferior longitudinal sinuses 
of the dura mater may be represented upon the external portion 
of the cranium by a line drawn over the middle line of the con- 
vexity of the skull from the root of the nose to the external occip- 
ital protuberance. 

The inferior longitudinal sinus runs along the free margin of 
the falx cerebri and opens into the anterior extremity of the 
straight sinus, behind the venae Galeni. 

The straight sinus runs downwards and backwards along the 
line of junction of the falx cerebri with the tentorium cerebelli 
and opens into the torcular Herophili. It receives blood from the 
venae Galeni, the inferior longitudinal sinus, the inferior median 
cerebral vein, and the superior cerebellar veins. 

The circular sinus is enclosed in a ring of dura mater, which 
surrounds the pituitary body. Its posterior half is larger in cali- 
bre than its anterior. 

The transverse sinus crosses the basilar groove and connects 
the two cavernous and inferior petrosal sinuses of either side. It 
is sometimes double. 

The occipital sinuses are contained in the falx cerebelli, and, 



424 



ANGIOLOGY. 



passing backwards and upwards from the posterior border of the 
foramen magnum, they open into the torcular Herophili. 

The lateral sinuses commence at the torcular Herophili and 
pass outwards, upon either side of this cavity, in the posterior 
attached margin of the tentorium cerebelli to the base of the 
petrous portion of the temporal bone ; they then curve down- 
wards and inwards in a groove in the mastoid portion of the 
temporal bone, and also in the occipital bone, and terminate, at 
the jugular foramen, in the internal jugular vein. These sinuses 
receive blood from the cavernous sinus, through the superior and 
inferior petrosal sinuses, and, from the inferior cerebral and the 
inferior cerebellar veins, and, occasionally, from some veins of the 
diploe. 

The course of the greater part of the lateral sinuses of the 
dura mater corresponds to a line drawn upon the external por- 
tion of the skull from the external occipital protuberance to the 
anterior border of the mastoid process. 

The cavernous sinuses are large and short. They extend, on 
either side of the sella turcica, from the sphenoidal fissure to the 
apex of the petrous portion of the temporal bone. They com- 
municate with each other, through the circular and transverse 
sinuses, and, with the lateral sinuses, by the two petrosal sinuses. 
In the inner wall of this sinus, separated from the blood by the 
lining membrane of the sinus, are the following structures, viz. 
The internal carotid artery, the 6th nerve, the carotid and cavern- 
ous plexuses of the sympathetic system. In the outer wall of this 
sinus, are enclosed the following structures, in their order from 
above downwards and from without inwards ; viz., the third, the 
fourth, and the ophthalmic nerves. 

The superior petrosal sinuses extend along the upper border 
of the petrous portion of the temporal bone, and are enclosed by 
the tentorium cerebelli. They serve to connect the cavernous and 
the lateral sinuses of the same side. 

The inferior petrosal sinuses lie in a groove in the petro-occipi- 
tal suture of the skull, and serve to connect the cavernous sinus 
of either side with the points of termination of the lateral sinuses, 
in the jugular foramina. 

The EXTERNAL JUGULAR vein commences in the substance 
of the parotid gland and descends down the neck superficially, to 
open into the subclavian vein. It has two valves, one situated at 
its point of termination, the other about an inch and a half above 
the clavicle. 

The external jugular vein is the chief superficial vein of the 



VEINS OF THE TRUNK. 



425 



neck and it is rendered prominent by putting the sterno-mastoid 
muscle into action, or by anything creating pressure upon the 
lower end of the vein, which corresponds with the middle of the 
clavicle. 

The INTERNAL JUGULAR vein is a continuation of the lateral 
sinus of the skull. It extends from the jugular foramen, down- 
wards, to the subclavian vein, where it has one pair of valves. 
This vein is in relation with the internal carotid artery and the 
common carotid artery, being contained in the sheath of the lat- 
ter vessel, and also with the 9th, 10th, nth and 12th pairs of 
cranial nerves (according to the classification of Soemmering). 

The RIGHT INNOMINATE vein is an inch and a half in length, 
is smaller than that of the left side, and is nearly vertical in direc- 
tion. It is separated from the right lung by the pleura and the 
right phrenic nerve. It joins the left innominate vein, below the 
cartilage of the first rib, to form the superior vena cava. 

The LEFT INNOMINATE vein is three inches in length, and de- 
cends obliquely from the left stemo-clavicular articulation to its 
point of junction with the right innominate vein. 

The SUPERIOR VENA CAVA is a thick trunk, about three inches 
in length, which enters the pericardial sac, about an inch and a 
.half above the heart, and terminates at the upper and front part 
of the right auricle. It has no valves. 

The INFERIOR VENA CAVA is formed by the junction of the 
two common iliac veins, at the right side of and between the 4th 
and $th lumbar vertebrcE. It lies on the right side of the abdom- 
inal aorta and passes behind the border of the mesentery, the 
transverse portion of the duodenum, the pancreas, and the portal 
vein. It is also lodged in a groove in the posterior border of the 
liver, where the hepatic veins join it. It perforates the central 
tendon of the diaphragm and thus enters the pericardial sac ; and 
subsequently terminates at the lower and back part of the right 
auricle of the heart. Its length is about eight inches. 

THE AZYGOS VEINS. 

These veins serve as a connecting link between the superior 
and inferior vena? Cavce. They also collect the blood from the 
intercostal spaces. They are three in number, and are called as 
follows. 

Vena azygos major, or right azvgos. 

Vena azygos minor, or left lower azvgos. 

Left superior azvgos. 



426 ANGIOLOGY. 

The right vena azygos arises either from the lumbar vein, the 
inferior vena cava, or the right renal vein. It passes through the 
aortic opening of the diaphragm, and here lies upon the right side 
of the thoracic duct, and behind and to the right of the aorta. It 
empties into the superior vena cava, on a level with the 3d dor- 
sal vertebra, having previously received the ten lower intercostal 
veins of the right side, the vena azygos minor, the right bronch- 
ial vein, and several small oesophageal, mediastinal and spinal 
veins. 

The vena azygos minor arises either from the left lumbar vein 
or from the left renal vein. It leaves the abdominal cavity 
through an opening in the left cms of the diaphragm, and, having 
collected the blood of the five lower intercostal veins of the left 
side, and some small mediastinal, oesophageal, and spinal veins, it 
crosses the spinal column behind the aorta and the thoracic duct 
and opens into the vena azygos major, on a level with the 6th 
dorsal vertebra. 

The left superior azygos vein collects the blood from the upper 
intercostal veins of the left side, and terminates in the vena 
azygos major. It may be absent. 

PORTAL SYSTEM OF VEINS. 

The portal vein, which carries blood to the transverse fissure 
of the liver, is formed by the junction of four large veins, viz. : 
Gastric vein. 
Splenic vein. 

Superior mesenteric vein. 
Inferior mesenteric vein. 
The gastric vein empties the blood of the stomach either into 
the main portal trunk or into the right branch of the portal vein. 
The splenic vein arises by five or six branches, which emerge 
from the hilum of the spleen ; and it also receives blood from 
the veins which correspond to the branches of the splenic artery. 
The superior mesenteric vein receives blood from those veins 
which correspond to the branches of the artery of the same name. 
The inferior mesenteric vein also receives, as tributaries, veins 
corresponding to the branches of the artery of the same name. 
This vein affords an outlet, in the rectum, for portal blood, in 
case of portal obstruction. 

The portal system will be considered, in detail, under the de- 
scription of the liver. 



VEINS OF THE PELVIS. 



VEINS OF THE PELVIS. 



427 



Internal Iliac 

(n tributaries.) 



The veins of the pelvis include the internal iliac veins and 
those veins which correspond to the branches of the artery of the 
same name, with the exception of the umbilical arteries. These 
veins may be enumerated as follows : 

f Hemorrhoidal. 
( Vesical. 

Visceral branches ■{ Prostatic. 

1 Uterine. 
[Vaginal. 

f Obturator, 
j Sciatic. 

Non-visceral branches . . . . ■{ TV , , 

) Ilio-lumbar. 

Lateral sacral. 

[Gluteal. 

The hemorrhoidal veins, as before mentioned, are of special 
importance, since they afford a point of communication betzveen 
the portal system of veins and the general system of veins. 

The vesical and the prostatic veins often join together to form 
a single vein, called the vesico-prostatic vein. 

The other veins, enumerated in the table, follow the course 
of the arteries of the same name. 

VEINS OF THE UPPER EXTREMITY. 

The veins of the upper extremity consist of a superficial 
and a deep set. The two sets include the following veins. 

f Radial. 

Anterior ulnar. 

Posterior ulnar. 

Median, 
j Median cephalic. 

Median basilic. 

Cephalic. 

Basilic. 



Superficial Veins. (8)1 



DeEPVE.NS (2)1S^™L 



/ Subcls 



avian vein. 



In addition to the deep veins above mentioned, there are 
vena comites to each of the arteries, except the axillary and the 
subclavian. 

Many of the veins included in the superficial and the deep 
sets of the upper extremity, require no special consideration, as 
their name indicates their situation. 

The relation of the median cephalic and the median basilic veins 
to the brachial artery, at the bend of the elbow, give to these veins 



428 ANGIOLOGY. 

a surgical importance, as venesection is most often performed in 
this locality. 

The cephalic vein ascends the arm in a groove at the outer side 
of the biceps muscle, and ends in the axillary vein, between the 
coracoid process of the scapula and the clavicle. It has one pair 
of valves at its point of termination. 

The basilic vein ascends the arm in a groove at the inner side 
of the biceps muscle, and terminates in the axillary vein, with 
which it is continuous. 

The axillary vein corresponds, in its situation and length, with 
the artery of the same name. It lies upon the inner side of this 
vessel. 

The subclavian vein, which is the direct continuation of the 
axillary vein, also corresponds, in length and direction, with the 
artery of the same name. Its relations to the artery, however, 
are slightly different in the three portions of that vessel, but it 
lies, as a rule, in front of the artery and on a plane below it. It 
receives, in addition to the blood from the arm, the contents of 
the external, the internal, and the anterior jugular veins. 

VEINS OF THE LOWER EXTREMITY. 

The veins of the lower extremity consist of a superficial and a 
deep set. These two sets include the following veins : 

e„™ n n,y,,iT v.,„, /„\ S External or short saphenous. 
Superficial Veins. .(2) \ T t , , f 

v ' ( Internal or long saphenous. 

C Popliteal. 

Deep Veins (3) -j Femoral. 

( External iliac. 

The short saphenous vein extends from the outer side of the 
dorsum of the foot and opens into the popliteal vein. It has two 
valves, near to its point of termination. 

The long saphenous vein extends from the inner side of the 
dorsum of the foot and opens into the femoral vein, at a point 
about one and a half inches below Poupart's ligament. This vein 
accompanies the long saphenous nerve, for the greater portion of 
its course, and contains from two to six valves, which are most 
abundant in the thigh. 

The popliteal vein lies superficial and external to the artery 
of the same name. It receives the blood from the short saphe- 
nous vein, and the venae comites of the arteries of the leg. 

The femoral vein lies posteriorly to the artery, in Hunter's 
canal, but reaches the inner side of that vessel, in Scarpa'.s space. 



VEINS OF LOWER EXTREMITY. 



429 



It receives the blood from the long saphenous vein as well as 
from those veins, which correspond to the branches of the artery 
of the same name. 

The external iliac vein differs, in its relation to the artery of 
the same name, upon the two sides of the body. It receives the 
blood of the epigastric and circumflex iliac veins, and joins with 
the internal iliac vein to form the common iliac veins. Its points 
of surgical interest will be found under the description of the ex- 
ternal iliac artery. 



43 o ANGIOLOGY. 



THE LYMPHATIC SYSTEM. 

The lymphatic system of the body possesses the property of 
absorbing certain materials from the tissues and conveying them 
into the circulation. The name " lymphatics " was originally ap- 
plied to these vessels from the appearance of the fluid which is 
contained within them, which has a resemblance to water {lym- 
pha, water). 

The lymphatic system includes various glands, called lym- 
phatic glands, through which the lymphatic vessels pass ; also 
innumerable small lymphatic vessels, which are scattered through- 
out every part of the body ; and, finally, the lacteal vessels, which 
are the lymphatic vessels of the small intestines, but to which the 
name lacteals was applied, from the fact that they contained a 
milky fluid after or during the process of digestion. These lac- 
teal vessels also pass through glands, called mesenteric glands, and 
finally, empty their contents, through the thoracic duct, into the 
subclavian vein of the left side. 

The coats of the lymphatic vessels are delicate and nearly 
transparent, and the fluid, contained within them, can be readily 
perceived through their walls. They contain a few valves, which 
are located regularly along their course, and which give to the 
lymphatic vessels an occasionally beaded appearance. 

In almost all portions of the body the lymphatic vessels are 
arranged in a superficial and a deep set, the former of which lie 
either near the integument or in the submucous tissue, while the 
latter lie in close relation to the larger blood-vessels, and, al- 
though fewer in number, are individually of larger size than those 
of the superficial set. These two sets, however, frequently com- 
municate with each other, and, in their total aggregate, vastly 
exceed the veins in number, but as a rule are much smaller in size. 

Certain structures in the body are said to be destitute of lym- 
phatics, among which may be mentioned, the substance of the 
brain and spinal cord, the tendons of muscles, cartilage, the eye, 
the nails, the hair, the placenta, and the umbilical cord. 

The lympJiatic glands, called also conglobate glands, are usually 
of a pinkish gray color, to which rule there are but few exceptions, 
and are situated in the course of the lymphatic and lacteal ves- 
sels. They usually have a hilus along one border and are divided 
into a cortical and medullary portion ; the latter occupying the 
centre of the gland except at the hilus, where it becomes super- 
ficially situated. The vessel which supplies the gland, previous 



IMPOR TANT L YMPHA TIC VESSELS. 43 1 

to its entrance, divides into branches, which are called the affer- 
ent vessels of the gland, and the vessels which escape from the 
glands are called the efferent vessels. Within the gland the lym- 
phatics form a plexus and are much thinner than elsewhere, since 
they lose their external coat, which becomes continuous with the 
capsule of the gland. 

The largest vessels of the lymphatic system are known as the 
thoracic duct and the right lymphatic duct. 

The THORACIC DUCT commences in a dilated pouch, called 
the receptaculinn chyli, which lies in front of the 2d lumbar ver- 
tebra, behind the aorta and between it and the vena azygos 
major. It receives the trunks of all lacteal vessels and four or 
five large trunks, from the lumbar lymphatic glands. It passes 
through the aortic opening of the diaphragm, and, in its course 
through the chest, is situated behind the oesophagus, and for a 
portion of its course, between the aorta and the vena azygos 
major. On a level with the 4th dorsal vertebra, it inclines towards 
the left side of the body and passes behind the arch of the aorta 
and the first portion of the left subclavian artery. On a level 
with the 7th cervical vertebra, it arches forwards above the pleura 
and in front of the scalenus anticus muscle, and opens into the 
angle of junction of the left internal jugular and the left subcla- 
vian veins, which opening is guarded by a pair of valves. Through- 
out its course it contains valves which give it, at intervals, a con- 
stricted appearance, and it also varies in its size, being largest at 
its upper and lower portions. It is the common trunk of all the 
lymphatics of the body, excepting those of the right side of the 
head, neck, and thorax, and the right upper limb, right lung, right 
side of the heart, and part of the convex surface of the liver. 
It is about sixteen and a half inches long. 

The RIGHT LYMPHATIC DUCT is a short thick trunk, about 
one line and a half in diameter, and about one inch in length, which 
collects the lymph from those portions of the body, which are 
unconnected with the thoracic duct. It opens into the angle 
of junction between the right internal jugular and the right 
subclavian veins, this opening being also guarded, as on the left 
side of the body, by a pair of valves. 

The lymphatics of the head and neck consist of superficial and 
deep lymphatic vessels and superficial and deep lymphatic glands. 
The important vessels accompany the larger arterial trunks of 
the head and neck, while the glands are principally situated in 
the lateral regions of the neck and in the vicinity of the base ot 
the skull and the angle of the lower jaw. 



432 



ANGIOLOGY. 



The lymphatics of the thorax maybe divided into those situa- 
ted upon the walls of the chest and those connected with the 
viscera. The parietal set are arranged, as in other portions of 
the body, into a superficial and a deep layer of lymphatic glands 
and vessels; while the visceral lymphatics are connected with the 
lungs and bronchi, the heart, the oesophagus, and the thymus 
gland. 

The lymphatics of the upper extremity comprise a superficial 
and a deep layer of lymphatic vessels and a superficial and a 
deep layer of lymphatic glands. The superficial layer of 
lymphatic vessels are more numerous upon the inner than upon 
the outer side of the arm ; while the deep layer of vessels ac- 
company the larger arteries of the forearm and of the arm, and 
open into the glands of the axilla and the subclavian region. 

The lymphatic glands of the upper extremity comprise two 
or three small superficial glands, in the vicinity of the inner con- 
dyle of the humerus, and a chain of deep lymphatic glands, which 
are most abundant in the vicinity of the brachial, axillary, and, 
subclavian arteries. 

The lymphatics of the abdomen, like those of the chest, com- 
prise a parietal set and a visceral set. The parietal set are situa- 
ted in the hypogastric, lumbar, and epigastric regions, and accom- 
pany the epigastric, the circumflex iliac, and the lumbar arteries. 
The visceral set are connected with the following organs : i. prin- 
cipally with the intestine, where they number over one hundred, 
and are called the mesenteric glands ; 2. with the liver, where 
they are arranged upon its upper surface, its under surface, and 
in the portal canals ; 3. in the stomacJi, where they are placed 
beneath the peritoneum and also in the submucous coat ; 4. in the 
spleen, where they form a superficial and a deep set ; and 5. in the 
kidney, where a superficial and deep set is also present. 

The lymphatics of the pelvic cavity consist of glands and lym- 
phatic vessels. The vessels are distributed over the entire sur- 
faces of the various organs of the pelvis, while the glands form 
chains upon the external and internal iliac arteries, and are also 
present in large numbers upon the sacrum and in front of the 
lumbar vertebrae. 

The lymphatics of the lozver extremity comprise a superficial 
and a deep set of vessels, and a superficial and a deep set of 
glands. The superficial lymphatic vessels arise from the integu- 
ment of the foot and terminate either in the lymphatic glands of 
the groin or of the popliteal space ; while the deep set of lym- 
phatic vessels accompany the tibial and peroneal arteries in the 



L YMPHA TIC SYSTEM. 



433 



leg, and the gluteal and sciatic vessels in the upper portion of the 
thigh. The efferent vessels of the popliteal glands accompany the 
femoral artery. 

The superficial lymphatic glands of the lower extremity are 
nine or ten in number, and are situated in the vicinity of Poupart's 
ligament and the upper portion of the saphenous vein ; while the 
deep set of lymphatic glands are chiefly distributed along the 
anterior tibial, the popliteal, the gluteal, and the sciatic arteries, 
while a few small glands accompany the femoral artery and com- 
municate, through the saphenous opening, with the superficial 
set. 



NEUROLOGY. 



NEUROLOGY. 

Nerve tissue consists of two varieties, viz., grey and white 
matter. The grey matter is found principally in the nerve centres 
and in the various ganglia. 

By some anatomists the nerve tissue, found in the sympathetic 
system of nerves, is considered as a separate form, and is called 
gelatinous nerve tissue. 

The grey nerve tissue is often called the vesicular nervous sub- 
stance, as it consists of vesicles, called nerve corpuscles, imbedded 
in a fine granular substance. 

The white nerve tissue is also called the fibrous or tubular 
nerve substance, since it exists in the form of nerve fibres. 

Each nerve is a bundle of nerve fibres bound together in a 
sheath, formed of connective tissue and called the perineurium. 
Each of the primitive nerve fibres are also enclosed in a sheath, 
which is more delicate than the perineurium and which is termed 
the neurilemma or epineurium. 

NERVES are divided, on a basis of their distribution, into those 
of animal life and those of organic life. The former subserve the 
higher functions of special sense, volition, sensation, etc. ; while 
the latter control nutrition and growth. 

The nervous system of animal life consists of two principal 
parts, as follows : 

1. A central portion, called the CEREBRO-SPINAL AXIS. 

2. A peripheral portion, called NERVES, GANGLIA, ETC. 



CEREBRO-SPINAL AXIS. 

This portion of the nervous system is, conventionally, divided 

into five parts, namely : 
* 

The Cerebrum. 
The Cerebellum. 
The Pons Varolii. 
The Medulla Oblongata. 
The Spinal Cord. 

Of these five parts, which make up the cerebro-spinal axis, the 
first four are contained within the cavity of the cranium, viz. : 
the cerebrum, cerebellum, pons Varolii, and medulla oblongata ; 
and, when taken collectively, are called the encephalon or brain. 

The encephalon extends to the upper border of the atlas or ist 



438 NEUROLOGY. 

cervical vertebra, at which point it becomes continuous with the 
spinal cord. 

The spinal cord extends from the plane of the upper border 
of the atlas to the lower part of the 1st, or the upper part of the 
2nd lumbar vertebra,where it becomes divided into a bundle of 
nerves, called, from their resemblance to a horse's tail, the cauda 
equina, and terminates in a slender filament, called the filum ter- 
minate or central ligament of the spinal cord. 

The nerves, which proceed from the cerebro-spinal axis, are 
43 in number, and are symmetrically arranged upon either side 
of the body. They may be divided as follows : 

A. Cranial Nerves Twelve pairs 12 pairs. 

f Cervical 8 " 

j Dorsal 12 " 

B. Spinal Nerves. (31 pairs.) \ Lumbar .5 " 

I Sacral 5 " 

[ Coccygeal 1 " 

Total, 43 " 

A cerebral or cranial nerve is one which arises from some 
portion of the cerebro-spinal axis, and which passes through one or 
more foramina of the cranium. They are named, in numerical 
order, from before backwards, in the order in which they escape 
from the base of the cranium. 

The term cerebrospinal nerve, is applied to any nerve, which 
arises from any portion of the cerebro-spinal axis ; and is used in 
contra-distinction to the nerves derived from the sympathetic 
system of the body. 

Each of the nerve filaments of the cerebro-spinal system, ex- 
cepting in the substance of the brain and the spinal cord, is com- 
posed of the following parts : 

A sheath, called the neurilemma or epineurium. 

A central portion, called the axis cylinder, which is composed 
of grey nerve matter. 

An investing substance of a whitish color, called the " white 
substance of Schwann," which is situated between the 
neurilemma and the axis-cylinder. This substance is 
not always present. It is often called the medullary 
sheath, and also the endoneuriutn of the nerve. 

The small isolated spots on cerebro-spinal nerves where the 
white substance of Schwann is wanting, are called nodes of Ran- 
vier. In the olfactory nerves, although belonging to the cerebro- 
spinal system, the white substance of Schwann is absent through- 
out their entire extent. 



GENERAL INTRODUCTION. 



439 



The sensory nerves of the cerebrospinal axis are found to ter- 
minate in one of four ways, as follows : 
In plexuses. 
In end-bulbs. 
In tactile corpuscles. 
In Pacinian bodies. 
The motor nerves terminate in small expansions within the 
muscles termed motorial end-plates. 

The nerves oi the sympathetic system, on the other hand, are dis- 
tinguished from cerebro-spinal nerves by their reddish grey color, 
their smaller size, and their softer consistence. 

Cerebro-spinal nerves are divided into two great classes, on a 
basis of their function, called respectively the motor and the sen- 
sory nerves. To the latter class, collections of grey nerve matter, 
called ganglia, are often attached. 

Membranes. 

The coverings of the brain and the spinal cord are three in 
number and are called, 

ist. The dura mater. 

2nd. The pia mater. 

3rdi The arachnoid. 

The dura mater is a thick, dense, fibrous membrane, which is 

lined, internally, by the parietal layer of the arachnoid. It serves, 

in the cranium, the following purposes : • 

1. It acts as a periosteal covering to the interior of the skull. 

2. It protects the brain from possible injury, especially in early 

life, when the bones of the cranium are separate and 
imperfectly formed. 

3. It supports the principal divisions of the encephalon by 

forming septa, which are lodged between its different 
portions. 

4. It assists in forming venous sinuses. 

5. It furnishes sheaths of protection for nerves. 

The dura mater of the brain differs from that of the spinal 
cord, in not performing the first, third, and fourth of the above- 
mentioned functions. 

These reflections or septa formed by the dura mater of the 
brain are called, 

T. The falx cerebri. 

2. The falx cerebelli. 

3. The tentorium cerebelli. 



440 NEUROLOGY. 

The arachnoid is, like all serous membranes, a shut sac which 
serves the purpose of lubricatioii and which invests the cerebro- 
spinal axis. The surface which invests the organs is called the 
visceral layer, while the surface which lines the dura mater is 
called the parietal layer. 

Between the visceral layer of the arachnoid and the pia 
mater, a cavity exists called the subarachnoidean space, which 
usually communicates with the general ventricular cavity in the 
brain substance, through an opening in the floor of the 4th ven- 
tricle. This space is most extensively developed at the base of 
the brain and around the spinal cord. It contains the cerebro- 
spinal fluid. 

The pia mater is a delicate vascular membrane which invests 
the brain and spinal cord, and whose function is that of nutrition. 
It is everywhere intimately adherent to the nerve substance, and, 
at the transverse fissure of the brain, it penetrates into the ven- 
tricular cavities of that organ and forms the choroid plexuses and 
the velum interpositum. 

The pia mater of the spinal cord differs from that which in- 
vests the brain, in being thicker, less vascular, and in forming a 
series of ligaments, called the ligament a denticulata, which unite 
the sides of the cord to the dura mater, and thus support it and 
protect it from injury. 



THE BRAIN OR ENCEPHALON. 



441 



THE BRAIN OR ENCEPHALON. 

The brain forms the largest part of the cerebro-spinal axis and 
is contained in the cavity of the skull. 

In order to remove the brain, for the purposes of examination, 
the following structures have to be divided : 

1. The scalp. 

2. The calvarium and the two temporal muscles. 

3. The three membranes or meninges. 

4. The twelve cranial nerves. 

5. The four arterial trunks, viz. : the two internal car- 

otid and the two vertebral arteries. 

6. The cerebral veins and sinuses. 

7. The medulla oblongata, at its junction with the 

spinal cord. 




DIAGRAM OF THE BRAIN IN PROFILE. 



This cerebrum is represented in this diagram as separated from the cerebellum 
more than it naturally should be, in order to show certain important parts. A, the 
cerebrum ; B, the cerebellum; C, the pons Varolii ; D, the medulla oblongata : E, the 
cms cerebri ; F ', the olivary body ; G, the tubercula quadrigemina s S, the fissure of 
Sylvius; R, the fissure of Rolando ; a, peduncles of cerebrum ; b, superior pe 
the cerebellum ; c, middle peduncle of the cerebellum ; d, inferior peditK. 
lum ; b, E, a, form the istlimus cneephali. 



442 NEUROLOGY. 

GANGLIA. 

The brain consists of twelve distinct ganglias, which may be 
enumerated as follows : 

{Cerebrum. 
Cerebellum. 
Medulla oblongata. 

f Olfactory bulbs (2). 

I Corpora striata (2). 

Nine smaller ganglia. . (9) . \ Optic thalami (2). 



Total, 12 



Tubercula quadrigemina (2). 
I Tuber annulare. 



The CEREBRUM fills the greater part of the cavity of the skull, 
excepting the posterior fossa which contains the cerebellum and 
the medulla oblongata. It consists of two distinct lateral halves, 
called the hemispheres of the cerebrum, which are separated by a 
longitudinal fissure. This fissure contains one of the prolonga- 
tions or septa formed by the dura mater, called the falx cerebri. 
The anterior and middle portions of each hemisphere rest on the 
bony floor of the skull, while the posterior portion of each is sep- 
arated from the upper surface of the hemispheres of the cerebel- 
lum by a prolongation of the dura mater, called the tentorium 
cerebelli, which affords it support and prevents injury to the brain 
in case of concussion being transmitted to it through the spinal 
column. 

The cerebellum lies within the posterior fossa of the skull and 
is divided into two lateral hemispheres, which are connected by a 
median lobe. It is in relation, above, with the posterior portion 
of the cerebrum ; and, in front, with the medulla oblongata. 

The medulla oblongata is the upper enlarged part of the spinal 
cord. It is contained in the posterior fossa of the skull ; lying 
upon the basilar groove of the occipital bone and situated ante- 
rior to the cerebellum and between its two hemispheres. 

The olfactory bulbs are connected with the hemispheres of the 
cerebrum by two bands, called the olfactory tracts ; and are situ- 
ated upon either side of the cribriform plate of the ethmoid bone. 
As their name indicates, they are the two ganglia of the special 
sense of smell, and are connected with the olfactory nerves. 

The corpora striata are two ganglia, situated within the sub- 
stance of the hemispheres of the cerebrum, one on either side ; 
and which lie in front of the optic thalamus of each hemisphere* 
They are prominently seen upon the floor of each of the lateral 
ventricles of the brain. 

The optic thalami are two ganglia, placed within the substance 



COMMISSURES OF ENCEPHALON. 443 

of the hemispheres of the cerebrum posterior to the corpus stria- 
tum of either side. They assist to form the floor of the lateral 
ventricles and also the sides of the third ventricle of the brain. 

The tubercula quadrigemina are four small rounded eminences, 
separated by a crucial suture. They are considered as forming, 
together, two single ganglia. They are situated on the exterior 
of the brain, at or near the point of union of the cerebrum and 
cerebellum ; and they can be best exposed by lifting the posterior 
portion of the cerebrum from the tentorium cerebelli. The term 
nates and testes is frequently applied to them from, a fancied re- 
semblance to those parts in miniature. 

The tuber annulare is a ganglion situated in the substance of 
the pons Varolii. By some the term is used as synonomous with 
the pons Varolii ; while, by others it is regarded only as its dis- 
tinct ganglionic centre. 

Later on, in a description of the component parts of the 
brain in detail, many points pertaining to these ganglia will be 
considered, which are now omitted in this general description, 
since it is impossible to enter into detail without the frequent 
use of terms which have not, as yet, been mentioned. 

COMMISSURES. 

In addition to the ganglia, which we have been considering, 
certain connecting bands of brain substance exist, which are called 
commissures. These may be divided into two sets, viz : the longi- 
tudinal and the transverse. Each of these sets include portions 
of the brain, to which special names have been applied. 

f Olfactory tracts. 
Striae longitudinales. 
Taenia semicircularis. 
Crura cerebri. 

Processes e cerebello ad testes. 
Longitudinal commissures C 11 )^ Peduncles of the pineal gland. 



(Which lie with their long axis in the 
antero-posterior direction). 



Fornix. 
Infundibulum. 
Lamina cinerea. 
Gyrus fornicatus. 

Fasciculus unciform is. 



f Anterior of 3rd ventricle. 
Middle of 3rd ventricle. 
Posterior of 3rd ventricle. 
Corpus callosum. 

Transverse commissures (9) { Pons Varolii. 

(Which run in the transverse direction). .fYalvjgjfcY Vieussens. 

IfrfsTerior medullary velum, 



Optic commissure. 



Total, 20 



44 4 NEUROLOGY. 

These various commissures are situated in different portions 
of the brain, and the consideration of each, where deemed impor- 
tant, will be found in subsequent pages, under the description of 
those regions where they are chiefly developed. 

It will be seen by the preceding tables that the fornix is both 
a longitudinal and a transverse commissure. 

The brain is convoluted upon its external surface, in order to 
afford a larger expanse of grey nerve matter, which is most ex- 
tensively distributed to this region. Within its substance, it con- 
tains five cavities, which have been respectively named as follows. 
The two lateral ventricles. 
The third ventricle. 
The fourth ventricle. 
The fifth ventricle. 

The two lateral ventricles are contained in the two hemispheres 
of the cerebrum ; the fifth ventricle is situated between the two lat- 
eral ventricles ; the third ventricle is situated between the two 
optic thalami ; and the fourth ventricle is comprised between the 
cerebellum and the medulla oblojtgata. 

The two lateral ventricles and the fifth ventricle lie upon the 
same plane, within the brain substance; the third ventricle lies 
on a plane below that of the lateral ventricles, and reaches the 
floor of the brain ; while the fourth ventricles lies below the plane 
of the hemispheres of the cerebrum, being situated in the region 
of the medulla oblongata. 

The two lateral ventricles communicate with the third ventri- 
cle through the foramina of Monroe ; and the third ventricle 
communicates with the fourth ventricle, through a canal termed 
the iter e tertio ad quartum ventriculum. 

Each of these ventricles have special boundaries, which merit 
description. 

THE LATERAL VENTRICLES. 
These two cavites are situated within the substance of the 
hemispheres of the cerebrum. They can be best exposed by 
separating the hemispheres, and by dividing, at the bottom of the 
median fissure, the great transverse commissure of the hemis- 
pheres, called the corpus callosum, upon either side, at its line of 
junction with the cerebrum. A cavity will be thus perceived to 
exist within each hemisphere, which presents a central portion or 
body and three cornua. The various points of interest pertaining 
to the central cavity or body, can be best described by enumerat- 
ing- its boundaries. 



VENTRICLES OF ENCEPHALON. 445 

Lateral Ventricles (boundaries). 

In front Brain substance and anterior cornu. 

Behind. Brain substance and posterior cornu. 

Externally Brain substance and middle cornu. 

Internally Septum lucidum. 

Above Corpus callosum. 



Below (6 points of interest). 



f Corpus striatum. 
Taenia semicircularis. 
Optic thalamus. 
Choroid plexus of veins. 
Corpus fimbriatum. 
Fornix. 



Each of the lateral ventricles presents three prolongations 
into the brain substance which are known as the anterior, middle, 
and posterior cornua, and which have been mentioned in the 
boundaries of the main cavity. 

The anterior cornu passes forwards and outwards over the 
anterior extremity of the corpus striatum. 

The middle cornu is curved like the horn of a ram, and the 
direction of its five curves may be represented, in their order from 
the ventricle to its point of termination, by the initial letters, B. 
O. D. F. I. On its floor is seen, (1) an eminence called the hippo- 
campus major ; (2) a few rounded masses resembling the paw of 
an animal and called the pes hippocampi ; (3) an eminence called 
the pes accessorius or eminentia collateralis ; (4) a projection formed 
by a continuation of the posterior pillar of the fornix called the 
corpus fimbriatum ; (5) a continuation of the pia mater into the 
interior of the brain forming the choroid plexus ; (6) a serrated 
band of grey matter, the fascia dent at a ; and (7) the transverse 
fissure of the brain. 

The posterior cornu curves backwards, downwards and out- 
wards into the occipital lobe of the cerebrum, and then backwards, 
downwards and inwards. On its floor is a longitudinal eminence 
called the hippocampus minor. 

In the table of boundaries it will be perceived that upon the 
floor of each lateral ventricle are present two of the ganglia of the 
brain, viz., the corpus striatum and the optic thalamus; a semi- 
circular-shaped band of fibres between these ganglia called the 
tcenia semicircularis, which extends from the anterior cms of the 
fornix to the middle or descending cornu ; a plexus of veins de- 
rived from the pia-mater of the brain, and called the choroid 
plexus ; a portion of the corpus fimbriatum, which has been de- 
scribed in connection with the middle cornu ; and the fornix, 
which will receive a special description in subsequent pages of 
this volume. 



446 NEUROLOGY. 

THE THIRD VENTRICLE. 

This is a narrow median fissure comprised between the two 
optic thalami. Its floor is situated on a lower relative plane than 
that of the two lateral ventricles and is formed by the structures 
comprised in the inter -peduncular space at the base of the brain. 
It communicates with both the lateral and with the fourth ven- 
tricles. It is exposed by turning back the body of the fornix 
from the floor of the lateral ventricles, and by the subsequent re- 
moval of the velum interpositum, which forms the root of the 
ventricle. 



In front | C 



Third Ventricle (boundaries). 

Crura of fornix. 

Anlerior transverse commissure. 
n i' n J S Posterior transverse commissure. 

\ Iter e tertio ad quartum ventriculum. 

<,. , j The optic thalami. 

es * \ Peduncles of the pineal gland. 

., \ Velum interpositum (pia mater). 

Above \ Under surface of the fornix. 

\ Lamina cinerea. 
Tuber cinereum. 
Below (5 points of interest). . -I Infundibulum. 

Corpora albican tia. 
Posterior perforated space. 

This ventricle is crossed by three bands or commissures, called 
respectively, the anterior, the middle or soft, and the posterior 
commissures. The anterior is composed of white nerve sub- 
stance, the middle of gray or vesicular substance, and the poste- 
rior of white nerve tissue. 

Between the crura of the fornix and the optic thalami, in the an- 
terior portion of the ventricle, are the foramina of Monroe, which 
transmit the vessels of the velum interpositum to form the cho- 
roid plexuses of the lateral ventricles. 

On the floor, in the foetus, the cavity of the pituitary body 
communicates with this ventricle by a canal through the infun- 
dibulum. This canal sometimes remains pervious. 

Posteriorly, this ventricle communicates with the fourth ven- 
tricle by a passage, beneath the posterior commissure, called the 
iter e tertio ad quartum ventriculum. 

This ventricle of the brain may therefore possess four open- 
ings, as follows : 

Foramina of Monroe (2). 

Opening into the fourth ventricle. 

Opening of the infundibulum (in the foetus only). 



VENTRICLES OF ENCEPI1AL0N. 



447 



The points of interest pertaining to the floor of this ventricle 
will be found separately considered under the description of the 
under surface of the cerebrum. 

THE FOURTH VENTRICLE. 

This cavity of the brain is rhomboidal in form and is comprised 
between the posterior surface of the medulla oblongata and the 
cerebellum. It is enclosed, inferiorly, by the pia mater which 
binds these parts together. It is situated on a plane below the 
level of the base of the brain. It communicates with the cavity 
of the third ventricle by means of the iter e tertio ad quartum 
ventriculum or aqueduct of Sylvius ; and also with the sub-arach- 
noidean space of the brain and spinal cord, by means of an 
opening in the pia mater, near the floor of the ventricle. Into 
this cavity, the pia mater of the brain is prolonged as a vascular 
fold, called the choroid plexus, which derives its blood chiefly 
from the inferior cerebellar artery. 

By some authorities, this ventricle is considered to be a dilated 
portion of the central canal of the spinal cord ; and the aqueduct 
of Sylvius is also regarded as a continuation of the same canal. 

Fourth Ventricle (boundaries). 

In front. Posterior surface of medulla and pons Varolii. 

Behind Substance of the cerebellum. 

Valve of Vieussens. 



Above \ The cerebellum. 

! Above Processus e cerebello ad testes. 
,. . ( Posterior pyramids. 
Lelow \ Restiform bodies. 

The floor of this cavity presents for examination the following 
points, which have been specially named. 
The posterior median fissure. 

The orifice of the central canal of the spinal cord. 
The locus cceruleus (named from its blue tint). 
The tcenia violacea (also of blue color). 
The fasiculi teretes (two spindle-shaped elevations). 
Various eminences, indicating the position of the nuclei of 
origin of certain of the cranial nerves. 

Fifth Ventricle (boundaries). 

This ventricle is formed by a separation of the two layers of 
the septum lucidum and is situated between the two lateral ven- 
tricles. It is bounded, above, by the corpus callosum, and it 
usually contains fluid. In the foetus, it communicates with the 



448 



NEUROLOGY. 



cavity of the third ventricle, by an opening between the pillars 
of the fornix. 




DIAGRAM OF BRAIN IN TRANSVERSE VERTICAL 

SECTION. 



1. Crus cerebri. 

2. Internal capsule. 

3. Optic thalamus. 

4. Corpus striatum. 

C. C. Corpus callosum. 
L. N. Lenticular nucleus. 

5. Fissure of Sylvius. 



Fo. Gyrus fornicatus. 
F'. First frontal convolution. 
F v . Second frontal convolution. 
F'". Third frontal convolution. 
T\ First temporal convolution, 
T ;/ . Second temporal convolution. 
T"". Third temporal convolution. 
H. Gyrus hippocampi. 



THE CEREBRUM. 

The cerebrum, in man, constitutes the largest portion of the 
brain. Its upper surface is of an ovoidal form, broader behind 
than in front, convex in its general outline, and divided into two 
lateral halves or hemispheres, the right and left, by the great 
longitudinal fissure. This fissure extends throughout the entire 
length of the cerebrum in the middle line, reaching down to the 
base of the brain in front and behind, but interrupted in the mid- 
dle by a broad transverse commissure of white matter, the corpus 
callosum, which connects the two hemispheres together. This 
fissure lodges the falx cerebri, and indicates the original develop- 
ment of the brain by two lateral halves. 

Each hemisphere presents for examination an outer surface, 
which is convex, to corres r ond with the vault of the cranium ; an 



FISSURES OF CEREBRUM. 



449 



inner surface, flattened, and in contact with the opposite hemis- 
phere, the two inner surfaces forming the sides of the longitudinal 
fissure ; and an under surface or base, of more irregular form, which 
rests, in front, on the anterior and middle fossae at the base of the 
skull, and, behind, upon the tentorium cerebelli. 

Each hemisphere presents five principal lobes and four impor- 
tant fissures which mark the boundaries of each lobe. These may- 
be enumerated as follows : 

The Principal Lobes of the Cerebrum. 

Each hemisphere has five principal lobes, which are called the 
anterior or frontal lobe, the parietal lobe, the posterior or occipital 
lobe, the central lobe or the island of Reil, and the middle or 
temporo-sphenoidal lobe. 

The frontal lobe comprises the anterior half of the hemisphere 
and is bounded, below, by the fissure of Sylvius, and, behind, 
by the fissure of Rolando. Its lower portion rests upon the or- 
bital plate of the frontal bone and it has been called by some 
authors the orbital lobe. 

The parietal lobe is situated behind the frontal lobe, on the 
convexity of the cerebrum. It extends downwards as far as 
the fissure of Sylvius. It is bounded, in front, by the fissure of 
Rolando, and, behind, by the parieto-occipital fissure. 

The occipital lobe is separated from the parietal lobe by the 
parieto-occipital fissure and rests upon the tentorium cerebelli. 

The temporo-sphenoidal lobe projects into the middle fossa of 
the skull and lies below the parietal and the occipital lobes. It 
is bounded in front by the fissure of Sylvius. 

The central lobe is also called the island of Reil and lies in the 
fissure of Sylvius. It is triangular in shape and is overlapped by 
the frontal and the temporo-sphenoidal lobes. It consists of six 
short and straight convolutions, called the gyri operti. Internally 
it corresponds with the outer surface of the lenticular nucleus, 
and it is that part of the cortex of the brain which is in the 
most immediate proximity to the ganglia within the substance 
of the cerebrum. Externally it is concealed from view, because 
that portion of the cerebral hemisphere included between the two 
branches of the Sylvian fissure projects downward from above, 
and overhangs it like a cover. For that reason this portion is 
named the " operculum." 

The Principal Fissures of the Cerebrum. 
Each hemisphere of the cerebrum has four fissures on its ex- 



45o 



NEUROLOGY. 



ternal surface, called the median longitudinal, the fissure of Sylvi- 
us, the fissure of Rolando, and the external parietooccipital fissure. 

These fissures separate the lobes of the hemispheres and are of 
value in describing the situation of certain special- convolutions 
on the external surface* of the cerebrum. 

The median longitudinal fissure separates the two hemispheres 
of the cerebrum. 

The fissure of Sylvius extends from the anterior perforated 
space, at the base of the brain, to about the middle point on the 
outer edge of the hemisphere. It then divides into a short anterior 
or ascending limb, and a long posterior or horizontal limb. It con- 
tains the central lobe or island of Re il. The triangular-shaped por- 
tion of brain comprised between these two limbs is called the 
"operculum." 

The fissure of Rolando extends between the frontal and the 
parietal lobes, from the longitudinal fissure to the outer extremity 
of the horizontal limb of the fissure of Sylvius. It is accompanied 
by two convolutions having a similar direction, one in front of 
it and one behind, which are called the "anterior and posterior 
central convolutions" 

The external parieto-occipital fissure extends from the median 
longitudinal fissure, at a point midway between the origin of the 
fissure of Rolando and the posterior extremity of the hemisphere, 
on the external surface of the cerebrum, for a distance of about 
an inch. It may be often indistinctly defined. It marks the 
division between the parietal and occipital lobes. 

Inner Surface of the Cerebrum. 

If we open the great longitudinal fissure and look at the inner 
surface of the hemisphere, we see the general arched form of its 
convolutions. A little above the corpus callosum is an impor- 
tant longitudinal fissure — the fissura calloso-marginalis. It runs 
for some distance parallel with the upper border of trie corpus 
callosum, and then turns upward, in an ascending branch, to the 
upper border of the hemisphere. 

In the occipital portion of this surface is the fissura parieto- 
occipital, directed obliquely downward and forward, and the 
fissura calcarina, nearly horizontal. These two fissures meet in 
front at an acute angle, and include between them a wedge-shaped 
lobule, the cuneus. 

In front of the cuneus is a quadrangular lobule, the precuneus, 
bounded behind by the fissura parieto-occipitalis, and anteriorly 



INNER SURFACE OF CEREBRUM. 



45* 



by the ascending branch of the fissura calloso-marginalis. In 
front of the precuneus may also be perceived a region called the 
para-central lobule, because it corresponds in situation with the 




DIAGRAM OF BRAIN IN LONGITUDINAL MEDIAN 

SECTION. 



1. Calloso-marginal fissure. 

2. Parieto-occipital fissure. 

3. Calcarine fissure. 



A. Third ventricle. 

B. Fifth ventricle. 

D. Anterior crura of fornix. 



C. Cuneus. 

Q. Precuneus. 

P. Paracentral lobe. 



C. C. Corpus callosum. 



F. Gyrus fornicatus. 



fissure of Rolando, and the two central convolutions on the out- 
side of the brain. 

The most important feature pertaining to the inner surface of 
the cerebrum is a convolution which lies immediately above the 
corpus callosum. It is called the gyrus fornicatus, because it has 
an arched or vaulted form; and it encircles the corpus callosum, 
the cerebral ganglia, and the crus cerebri in a continuous longi- 
tudinal curve. 

It starts from the inferior part of the anterior lobe, just in front 
of the Sylvian fissure, and winds around the anterior extremity 
of the corpus callosum, and along its upper border. Here it is 
included between the corpus callosum, below, and the fissura 
calloso-marginalis above. It extends backward, in this part of its 
course, as a single independent convolution, as far as the ascend- 
ing branch of the fissura calloso-marginalis. It then curves round 
the posterior extremity of the corpus callosum, passes beneath 



45: 



ANGIOLOGY. 



the crus cerebri, and runs downward and forward to a point just 
behind the fissure of Sylvius, almost exactly opposite the place 
from which it started. In this lower portion of its course it is 
often designated as the " gyrus hippocampi." 

The Floor of the Brain. 

The base of the brain, upon its under surface, is formed mainly 
by the inferior surface of each hemisphere of the cerebrum. 

The various points of interest exposed to view, on the under 
surface of the cerebrum, in or near the median line, are here ar- 
ranged in the order in which they are met with, from before 
backwards. 

1. Longitudinal fissure. 7. Optic commissure. 

2. Corpus callosum and its pe- 8. Tuber Cinereum. 

duncles. 9. Infundibulum. 

3. Lamina cinerea. 10. Pituitary body. 

4. Olfactory nerves. II. Corpora albicantia. 

5. Fissure of Sylvius. 12. Posterior perforated space. 

6. Anterior perforated space. 13. Crura cerebri. 

The longitudinal fissure separates the two hemispheres of the 
cerebrum. 

The corpus callosum is the great transverse commissure of the 
brain and connects the two hemispheres. 

The lamina ci?ierea is a thin layer of grey matter which con- 
nects the corpus callosum with the tuber cinereum, passing be- 
neath each of the optic tracts, near the optic commissure. 

The fissure of Sylvius separates the anterior lobe of the cere- 
brum from the temporo-sphenoidal lobe and lodges the middle 
cerebral artery. It has been described in preceding pages. 

The anterior perforated space admits vessels to the corpora 
striata. 

The optic commissure or chiasm is formed by the union of the 
optic tracts, in front of the tuber cinereum. From it the two 
optic nerves are given off. It is composed of four varieties of 
fibres, as follows : 

1. The inter-cerebral fibres, which pass from one hemisphere 

of the cerebrum to the other. 

2. The inter-retinal fibres, which connect the retina of one eye 

with that of the other. 

3. Longitudinal fibres, which connect the brain with the retina 

of the same side. 

4. Decussating fibres, which connect the hemispheres of the 



INTERNAL PORTION OF CEREBRUM. 



453 



cerebrum with the retina of the opposite side ; and 
which cross each other at the point of union of the 
optic tracts. 

The tuber cinereum is a lamina of gray matter which extends 
from the corpora albicantia to the optic commissure, to which it 
is attached in front. In the median line, it is prolonged into the 
infundibulum. 

The infundibulum is a process of brain substance which con- 
nects the base of the brain at the floor of the third ventricle with 
the pituitary body. It is hollow, and, in the foetus, affords a chan- 
nel of communication between a cavity in the pituitary body and- 
the third ventricle of the brain. 

The corpora albicantia or mamillaria are two round, white 
eminences, situated in front of the posterior perforated space and 
united to each other in the median line. They are formed by the 
anterior crura of the fornix and are sometimes called the bulbs 
of the fornix. 

The posterior perforated space performs the same function for 
the optic thalami as did the anterior space for the corpora striata. 

The crura cerebri connect the cerebrum with the spinal cord, 
the cerebellum, and the medulla oblongata. Through them pass 
the fibres which enter the corpora striata and the optic thalami, 
and which subsequently radiate to the convolutions of the cere- 
brum. They form, in connection with the optic tracts, the bound- 
aries of a lozenge-shaped space, called the inter-peduncular space. 

The pituitary body lies in a cavity on the upper surface of the 
body of the sphenoid bone, called the sella turcica. 

Internal Parts of the Cerebrum. 

The white or peduncular fibres of the cerebrum connect (i) 
the grey matter of its surface with the anterior cerebral ganglia 
(the corpora striata and optic thalami), which fibres are called the 
corona radiata ; and (2) the interior cerebral ganglia with the. pojis 
Varolii, thus forming the crura cerebri. 

Within the hemispheres of the cerebrum are contained the 
following points of special interest : (1) the ventricles, whose points 
of interest have already been described; (2) four ganglia \ viz., the 
corpora striata and the optic thalami ; and (3) two great commis- 
sures, viz., the corpus callosum and the fornix. 

The corpus striatum is divided into two parts. One of them 
is the intra-ventricular portion, visible from the lateral ventricle, 
which has a bulging anterior extremity or head, and a slender 



454 



NEUROLOGY. 



posterior continuation, like a tail, called the " caudate nucleus" 
of the corpus striatum. The other part is the extra-ventricular 
portion. It is not visible from the lateral ventricle, but is im- 
bedded in the substance of the brain. In some planes of section 
it shows a tolerably regular lens-like figure, and is therefore called 
the u lenticular nucleus." According to this nomenclature, the 
optic thalamus is a separate and complete ganglion by itself; 
while the corpus striatum consists of two portions, namely, an 
intra-ventricular portion, or the caudate nucleus, and an extra- 
ventricular portion, or the lenticular nucleus. The name " corpus 
striatum " is often applied, however, to the intra-ventricular or 
caudate portion, while the other part is known simply as the 
"lenticular nucleus." 

The corpus striatum, if taken as a whole, has the shape of a ring 
if viewed laterally, after a section has been made which completely 
exposes the lateral ventricle and its prolongations into the brain 
substance. 

This annular form is due to the tail-like projection from the 
body of the ganglion, which curves over the posterior extremity 
of the optic thalamus and then descends into the inferior cornu of 
the ventricle, following its curve as far as the anterior extremity 
of that cornu. It thus encircles the crus cerebri and the internal 
capsule, and it is sometimes called the surcingle of the corpus stri- 
atum from this peculiarity in its course. 

That portion of white substance, running upward and outward, 
between the corpus striatum and the lenticular nucleus, is known 
as the " internal capsule." 

The corpus striatum differs from the optic thalamus in respect 
to the arrangement of its grey matter ; since, in the former, the 
nerve fibres pass through its gray matter in distinct bundles, while, 
in the latter, the fibres are intermixed with the gray matter giving 
it a uniform color and appearance. 

The thalamus opticus (posterior cerebral ganglion) is of oval 
shape and rests upon the corresponding crus of the hemispheres. 
It is bounded, on the outer side, by the corpus striatum and the 
taenia semicircularis. The part which is seen in the lateral ven- 
tricle is called the anterior tubercle ; while the part situated be- 
neath the fornix is called the posterior tubercle. Each of the 
thalami optici enters into the construction of both lateral ventri- 
cles and the third ventricle. Its gray matter is evenly distributed 
between the nerve fibres which pass through it, thus giving it a 
uniform color. 

The fornix is a longitudinal lamella of fibrous matter, situated 



INTERNAL PARTS OF CEREBRUM. 



455 



beneath the corpus callosum, with which it is continuous behind ; 
but it is separated from it, in front, by the septum lucidum. It 
may be described as consisting of two symmetrical halves, one for 
either hemisphere. These two portions are joined together, in the 
middle line, where they form the body of the fornix, but are sep- 
arated from one another in front and behind ; in front, formkig the 
anterior crura, and behind, the posterior crura of the fornix. 

The body of the fornix is triangular in form ; narrow in front, 
broad behind. Its upper surface is connected, in the median line, 
to the septum lucidum, in front, and the corpus callosum behind. 
Its under surface rests upon the velum interpositum, which sep- 
arates it from the third ventricle, and the inner portion of the 
optic thalami. Its lateral edges form, on each side, part of the 
floor of the lateral ventricles, and are in contact with the choroid 
plexuses. 

The anterior crura of the fornix arch downwards towards the 
base of the brain, separated from each other by a narrow interval. 
They are composed of white fibres, which descend through a 
quantity of grey matter in the lateral walls of the third ven- 
tricle, and are placed immediately behind the anterior commissure. 
At the base of the brain, the white fibres of each crus form a sud- 
den curve upon themselves, spread out and form the outer part 
of the corresponding corpus albicans. The anterior crura of the 
fornix are connected, in their course, with the optic commissure, 
the white fibres covering the optic thalamus, the peduncle of the 
pineal gland, and the superficial fibres of the taenia semicircularis. 

The posterior crura of the fornix, at their commencement, 
are intimately connected by their upper surfaces with the corpus 
callosum ; diverging from one another, they pass downwards into 
the descending horn of the lateral ventricle, being continuous 
with the concave border of the hippocampus major. The lateral 
thin edges of the posterior crura have received the name corpus 
fimbriatum, already described. On the under surface of the for- 
nix, towards its posterior part, between the diverging posterior 
crura, may be seen some transverse lines, and others longitudinal 
or oblique. This portion of the fornix has been termed the 
lyra, from the fancied resemblance it bears to the strings of a 
harp. 

Between the anterior pillars of the fornix and the anterior ex- 
tremities of the thalami optici, an oval aperture is seen on each 
side, the foramen of Monroe. These two openings descend to- 
wards the middle line, and, joining together, lead into the upper 
part of the third ventricle. These openings communicate with 



456 NEUROLOGY. 

the lateral ventricles on each side, and below with the third 
ventricle. 

The corpus callosum is a thick stratum of transverse fibres, ex- 
posed at the bottom of the longitudinal fissure. It connects the 
two hemispheres of the brain, forming their great transverse com- 
missure ; and forms the roof of a space in the interior of each 
hemisphere, the lateral ventricle. It is about four inches in 
length, extending to within an inch and a half of the anterior, and 
to within two inches and a half of the posterior part of the brain. 
It is somewhat broader behind than in front, and is thicker at 
either end than in its central part, and is thickest behind. It pre- 
sents a somewhat arched form, from before backwards, and termi- 
nates anteriorly in a rounded border, which curves downwards and 
backwards, between the anterior lobes to the base of the brain. 
In its course, it forms a distinct bend, named the knee or genu, 
and the reflected portion, named the beak or rostrum, is attached 
to the anterior cerebral lobe, and is connected, through the lamina 
cinerea, with the optic commissure. The reflected portion of the 
corpus callosum gives off, near its termination, two bundles of 
white substance, which, diverging from one another, pass back, 
wards, across the anterior perforated space, to the entrance of the 
fissure of Sylvius. They are called the peduncles of the corpus 
callosum. Posteriorly, the corpus callosum forms a thick, rounded 
fold, which is free for a little distance, as it curves forwards, and 
is then continuous with the fornix. On its upper surface, its 
fibrous structure is very apparent to the naked eye, being col- 
lected into coarse, transverse bundles. Along the middle line, is 
a linear depression, the raphe, bounded laterally by two or more 
slightly elevated longitudinal bands, called the strice lo?igitudin- 
ales or nerves of Lancisi ; and, still more externally, other longi- 
tudinal striae are seen, beneath the convolutions, which rest on 
the corpus callosum. These are the stria longitudinales laterales. 



THE MESO-CEPHALON. 

The parts which help to form the connecting link between the 
cerebrum, cerebellum, and medulla oblongata, when taken as a 
whole, are termed the meso-cephalon. Under this head certain 
parts are included which have been already described in detail, 
since they pertain chiefly to other regions, while some others 
have been only casually referred to. 

The meso-cephalon comprises the following structures : 



THE MESO-CEPHALON. 



457 



(i) The pons Varolii. 

(2) The crura cerebri. 

(3) The inferior peduncles of the cerebellum. 

(4) The superior peduncles of the cerebellum. 

(5) The valve of Vieussens. 

(6) The tubercula quadrigemina. 

(7) The pineal gland or conarium. 

The pons Varolii is the great transverse commissure which 
binds the hemispheres of the cerebellum to each other and to the 
medulla oblongata. It passes across the front of the medulla and 
lies on a plane between that of the superior and inferior peduncles 
of the cerebellum. Its lateral portions are often called the mid- 
dle peduncle of the cerebellum. 

The crura cerebri comprise the peduncular fibres of the cere- 
brum, in contra-distinction to the commissural fibres and the cor- 
ona radiata. They are three-quarters of an inch in length, and 
extend from the upper border of the pons Varolii to the corpora 
striata and the optic thalami. They are crossed by the optic 
tracts, and they form the posterior boundary of the inter-pedu?i- 
cular space. Each crus contains a central mass of grey matter 
called the locus niger. The fibres of each crus, which pass above 
this central mass, form a layer called the tegmentum, while those 
which pass below it form a bundle called the fasciculated portion. 

The valve of Vieussens is a thin lamina of white matter which 
forms the roof of the aqueduct of Sylvius. It presents a median 
ridge, called the frenulum. 

The tubercula quadrigemina (nates and testes) are situated 
above the valve of Vieussens and posterior to the third ventricle 
of the cerebrum. Bands of white matter, called brachia anteriora 
connect the two nates or anterior lobes with the optic thalami and 
the optic tracts ; while similar bands, called brachia posteriora con- 
nect the testes or posterior lobes with the same parts. The nates 
are larger and darker colored than the testes. 

The pineal gland or conarium is a small conical body of a red- 
dish-grey color situated between the nates. It has two processes 
on each side, called the superior and inferior peduncles of the pineal 
gland. The superior set run forwards over the inner surface oi 
each optic thalamus and become united to the anterior crura of 
the fornix; while the inferior set descend vertically upon the inner 
surface of each optic thalamus. This gland has one or two small 
cavities which often communicate with the third ventricle of the 
cerebrum. The contents of these cavities is termed the acen 
cerebri. 



458 



NEUROLOGY. 



THE MEDULLA OBLONGATA. 



This ganglion of the brain is the upper and enlarged part of 
the spinal cord and extends from the lower border of the pons 
Varolii to the point of decussation of the anterior pyramids of the 
spinal cord, which point corresponds nearly to the upper border 
of the atlas. Its anterior surface rests upon the basilar groove of 
the occipital bone, while its posterior surface forms a portion of 
the fourth ventricle and is continuous with the posterior surface 
of the spinal cord. 

The medulla oblongata is divided into two lateral halves by 
an anterior and a posterior median fissure, the former of which is 
interrupted, in part, by the decussations of the anterior pyramids. 

Each half of the medulla oblongata presents the following 
points to which a special name has been applied : 

1. The anterior pyramid, which is formed by the anterior and 

the lateral columns of the spinal cord. 

2. The olivary body, which is a prominent oval mass behind 

the pyramid, from which it is separated by a groove, 
called the groove of the hypoglossal nerve. 

3. The lateral tract, which lies behind the anterior pyramid 

and the olivary body and in front of the restiform body 
of the medulla. It is continuous with the lateral col- 
umn of the cord. The groove between it and the 
restiform body gives origin to the 9th, 10th, and nth 
nerves. 

4. The restiform body or the fasciculus cuneatus is the outer 

and larger portion of the posterior portion of the 
medulla. 

5. The posterior pyramid or fasciculus gracilis is the inner por- 

tion of the posterior part of the medulla and is chiefly 
formed by the fibres of the posterior columns of the 
spinal cord. It enters into the formation of the 4th 
ventricle of the brain. 
The grey matter of the medulla oblongata is scattered through- 
out its entire substance and has special interest, since, in the 4th 
ventricle, it affords separate nuclei, from which the 5th, 6th, 7th, 
8th, 9th, 10th, nth, and 12th nerves are said to arise either in 
part or entirely. 

In the medulla, are supposed to exist the nerve centres for the 
performance of the acts of respiration, deglutition, phonation, mas- 
tication, and expression ; and centres for the vaso-motor nerves 
of the sympathetic system and for the cardiac nerves. It will 



THE CEREBELLUM. 459 

thus be more clearly understood why injury to this ganglion is 
so rapidly fatal. 

THE CEREBELLUM. 

This ganglion of the brain is situated within the posterior fossa 
of the skull, and is in close relation, in front, with the medulla 
oblongata ; while, above, it is separated from the occipital lobe of 
the cerebrum by the tentorium cerebelli. 

In shape, this ganglion is oblong, from side to side, and flat- 
tened from above downwards. It therefore presents two surfaces, 
an upper and an lower surface, and a circumference. 

The cerebellum consists of two lateral lobes and a central or 
connecting lobe called the vermiform process. This central lobe 
is usually described as consisting of two parts, the superior and 
the inferior portion. 

Upper Surface of the Cerebellum. 

This surface presents for examination the following parts, 
which are specially named and which deserve enumeration. 

1. The upper surface of each lateral hemisphere. 

2. The superior surface of the vermiform process. 
Each lateral hemisphere may be seen to present, on its upper 

surface, two distinct portions. 

The anterior portion or the square lobe. 

The posterior portion or the semilunar lobe. 
The vermiform process, on the upper aspect, is also seen to 
present three slight elevations called respectively, from before 
backwards. 

The lobulus centralis. 

The monticulus cerebelli. 

The commissura simplex. 

Under Surface of the Cerebellum. 

This surface is rounded and elevated on the sides, and in the 
centre, it is depressed into a groove between the two lateral lobes 
of the cerebellum, which depression is called the vallecula or val- 
ley. It presents, as did the upper surface, the three following 
parts for examination. 

1. The under surface of each lateral hemisphere. 

2. The inferior surface of the vermiform process. 
The lateral hemispheres may be seen to present upon this 

surface, five distinct lobes, called as follows : 



46.0 



NEUROLOGY. 



The flocculus, sub-peduncular lobe, or pnemnogastnc 
lobule. 

The amygdala lobe or the tonsil. 
The digastric lobe. 
The slender lobe. 
The posterior inferior lobe. 
The vermiform process, on its under surface, presents the fol- 
lowing parts which have been specially named : 
The pyramid. 
The uvula. 

The commissura brevis, which connects the two sur- 
faces of the vermiform process. 

The Circumference of the Cerebellum. 

This portion of the cerebellum presents for examination the 
following parts : 

Two vertical fissures, called : 

The incisura cerebelli anterior. 
The incisura cerebelli posterior. 
A great horizontal fissure, which extends from the middle 
peduncle of one hemisphere to the same point upon 
the opposite side. 

Processes of the Cerebellum. 

The cerebellum is connected to the medulla oblongata, the 
pons Varolii, and the cerebrum, by three processes, which are 
called, from below upwards, as follows. 

The inferior, or processus e cerebello ad medullam. 
The middle, ox processus e cerebello ad pontem. 
The superior, or processus e cerebello ad testes. 
The grey matter of the cerebellum consists of three distinct 
parts or layers, as follows : 

(1) External layer of small cells, both round and polar in 
form, and nerve fibres. 

(2) Middle layer of cells with long processes penetrating into 
the external layer, called the cells of Purkinje. 

(3) Internal layer, called the granular layer, formed by dense 
masses of granular corpuscles. 



THE BRAIN ASA WHOLE. 46 1 



GENERAL SUMMARY. 

The grey matter of the brain is arranged in two main divisions, 
occupying two different localities. These divisions comprise : 
First, the exterior convolutions, forming the cortex of the brain 
and spread out upon its surface; and, secondly, the interior cere- 
bral ganglia, situated at its base, and known as the corpus stria- 
tum and optic thalamus. 

The white matter, on the other hand, is derived from a con- 
tinuation of the longitudinal columns of the spinal cord, which pass 
upward through the medulla oblongata to the interior cerebral 
ganglia and then continue their course to terminate in the convo- 
lutions. 

In the cerebro-spinal system, counting from without inward, 
there are three principal deposits or centres of grey matter: 

1st. The grey matter of the spinal cord, extending upward on 
the floor of the fourth ventricle, and around the aqueduct of Syl- 
vius, forming what is known as the grey matter of the medullary 
canal. 

2d. The interior cerebral ganglia at the base of the brain. 

3d. The convolutions of the hemispheres. 

There are also three sets of fibres, forming the white sub- 
stance : 

1st. The nerves and nerve-roots, connecting the external or- 
gans of the body with the grey matter of the medulla. 

2d. The fibres connecting the grey . matter of the medulla 
oblongata with the interior cerebral ganglia. 

3d. Those uniting the interior cerebral ganglia with the convo- 
lutions of the cortex. 

Of the nine ganglia, which have been named as the smaller 
ganglia of the brain, four are situated outside of the brain, viz., 
the two olfactory and the tubercula quadrigemina ; and five 
within the substance of the brain, viz., the corpus striatum of 
either side, the optic thalamus of either side, and the tuber annul- 
are, which is located in the substance of the pons Varolii. 

The copora striata enter into the formation of the lateral ven- 
tricles ; the optic thalami enter into the formation of both the 
lateral and the third ventricles. 

The tubercula quadrigemina can be exposed, by separating 
the posterior lobe of the cerebrum from the cerebellum, when it 
will be seen at the point of junction of the two. 

The sinuses of the brain have already been considered in the 
chapter upon the venous system. 



462 NEUROLOGY. 

The weight of the brain averages about 49 ounces in the male, 
and about 44 ounces in the female, but it appears to bear a gen- 
eral relation to the intellectual capacity of the individual. 

The spaces between the convolutions of the brain substance are 
called sulci. 

The so-called grey matter of the convolutions is arranged in 
alternate layers of grey and white nerve tissue, which vary from 
four to six in number. 

The cells of the brain are usually characterized by prolongations 
from their bodies and are therefore termed polar cells. They are 
divided, however, into four classes, viz., apolar, monopolar, bipo- 
lar and multipolar, in accordance with the number of poles 
which they present. 

The ventricles of the brain contain more or less fluid, which 
is called the ventricular fluid ; and the general ventricular cavity 
of the brain communicates, through a hole in the floor of the 
fourth ventricle, with the cavity of the subarachnoidean space. 

The level of the base of the anterior portion of the cerebrum 
corresponds to a line drawn between two points situated just 
above the external angular processes of the frontal bone. 

The axis of the base of the brain in the anterior and middle 
fosses of the skull may be approximately represented by a line 
drawn from the external angular process of the frontal bone to 
the upper part of the external auditory meatus. 

The level of the posterior lobe of the cerebrum corresponds 
to a line drawn from the upper part of the external auditory 
meatus to the external occipital protuberance. 

THE SPINAL CORD. 

The spinal cord is sixteen and a half inches long, and extends 
from the upper border of the atlas to the lower border of the 1st 
lumbar vertebra, where it terminates in the Cauda equina. It 
weighs one ounce and a half, when divested of its membranes. It 
presents two enlargements, situated in the cervical and the lum- 
bar regions, which are called the cervical and the lumbar en- 
largements. 

The spinal cord presents four columns, called the anterior, the 
lateral, the posterior, and the posterior-median columns ; and five 
fissures, called the antero-median, the postero-median, the an- 
terolateral, the postero-lateral, and, in the cervical region, a fis- 
sure, described by Sappey, called the postero-intermediary fissure. 

The spinal cord gives origin to thirty-one pairs of nerves, each 



THE SPINAL CORD. 



4^3 



of which arises by two roots, called the anterior and posterior 
roots, which subsequently unite to form a single nerve. 

The posterior root of each spinal nerve, being sensory in its 
function, has developed upon it, like all sensory nerves, a gang- 
lion. The anterior root has no ganglion, since it is a motor nerve. 

The grey matter of the spinal cord, which is best seen upon 
a transverse section of the cord, consists of two crescentic masses, 
each of which are situated in one of the lateral halves of the 
spinal cord, and which are joined together by a transverse commis- 
sure. These two crescentic masses form, by their extremities, 
the anterior and posterior horns of grey matter, within either half 
of the cord. In each of the posterior horns, a collection of cells 
at the extremity of the horn is termed the substantia gelatinosa ; 
while a group of cells at the inner side of the posterior horn, is 
called the posterior vescicular column. 

The anterior roots of the spinal nerves arise from the region 
of the anterior horn, while the posterior roots of the spinal nerves 
arise from the region of the posterior horn of grey matter. 

The thirty-one pairs of nerves, which are given off from the 
spinal cord, form, by their anterior branches, plexuses of nerves, 
in various parts of the body. The four most important plexuses, 
so formed, are called the cervical, the brachial, the lumbar, and 
the sacral plexuses. 

The nerve fibres of the posterior columns of the spinal cord 
decussate throughout the entire length of the cord, while those 
of the anterior columns decussate only in the medulla oblongata. 

The spinal cord is perforated, throughout its centre, by a 
canal, which opens, at its upper part, into the 4th ventricle of the 
brain, and which is lined, throughout, with columnar ciliated epi- 
thelium. 

The commissure of the spinal cord, which connects the two 
lateral halves and which limits the depth of the two median fis- 
sures of the cord, consists of two parts called the white and the 
grey commissures. The white commissure lies anteriorly ; and the 
grey commissure connects the cresentic masses of grey matter in 
the lateral halves of the cord. 

The zvhite nerve substance of the spinal cord entirely surrounds 
the grey matter except at the posterior grey commissure of the 
cord. 

The fibres of the columns of the spinal cord pass upwards and 
downwards for variable distances and connect the cells of the 
different segments of the cord together ; although some fibres 
are supposed to pass uninterruptedly upwards to the ganglia at 



464 



NEUROLOGY. 



the brain. These fibres are not to be confounded with the fibres 
of the spinal nerves, some of which are distributed in a totally dif- 
ferent manner within the substance of the cord, although some 
accompany the proper fibres of the columns. 

The fibres of the anterior columns of the spinal cord are chiefly 
prolonged into the anterior pyramid of the medulla oblongata, 
although they also assist to form the olivary fasciculus and the 
inferior peduncles of the cerebellum. 

The fibres of the lateral columns of the cord are prolonged into 
the pyramid of the medulla oblongata, and also in the fasciculi 
teretes and the inferior peduncle of the cerebellum. 

The fibres of the posterior columns of the cord are prolonged 
into the rest if or m bodies of the medulla oblongata, and the 
fasciculi teretes. 

The fibres of the roots of the spinal nerves are distributed within 
the substance of the spinal cord as follows. 

Those of the ANTERIOR ROOTS pass at first horizontally till 
they reach the anterior horn of grey matter, where they divide 
into three sets which are distributed as follows : 

Pass through the white commissure to the opposite side of the spinal 

(1) Internal set. \ cord. 
Are then distributed to the anterior and lateral columns of that side. 

Ascending fibres to gray substance of same side. 

(2) Middle set. 4 Descending fibres to gray substance of same side. 
Antero-posterior fibres to gray substance of same side. 

, v n j To anterior and lateral columns of the side of the spinal cord at 

{3) uuter set. -j whkh thg nerye entered> 

Those of the POSTERIOR ROOTS enter at first the substantia 
gelatinosa of the side opposite to the peripheral distribution of the 
nerve, since the posterior spinal fibres decussate ; and at that 
point they also divide into three sets, which are distributed as 
follows 

/ v qi ,. . j These fibres pass upwards and downwards in company with the 

^ ' " "I proper fibres of the columns of the spinal cord. 

, v T , ( Pass through the gray commissure of the cord to the opposite side. 

^ ' ' (Are then distributed to the lateral and posterior columns of that side. 

!To the anterior and lateral columns of that side of the spinal cord at 
which the nerve entered. These fibres intermingle with those 
of the anterior roots. 



THE CEREBRO-SPINAL NERVES. 

In the chapter of this work upon myology, a detailed descrip- 
tion has already been given to the reader of most of the import- 
ant motor nerves of the body; and many tables have been there 
incorporated which, by their classified arrangement, are intended 
to assist the anatomical student in mastering their points of dis- 
tribution. 

It is therefore been deemed unnecessary to again give, in 
detail, a separate distribution of those nerves, which already have 
been so exhaustively considered ; but, in place of it, is appended 
a tabulated arrangement of the nerves of the body, which illus- 
trates, with tolerable completeness and accuracy, all points which 
are of special value. 

Occasional explanatory text will be found introduced, between 
these various tables, for the purpose of attracting attention to 
some points of special interest included in them, or for the purpose 
of recording some facts, which cannot well be embraced in a 
tabular form of statement, without creating confusion. This text 
will only be found valuable, however, if used in conjunction with 
the tables which precede it. 

In these tables the nerves which arise from the cerebro-spinal 
axis will be found considered in the following order. 

A. The cranial nerves. 

B. The nerves of the cervical region. 

C. The nerves of the upper extremity. 

D. The nerves of the dorsal region. 

E. The nerves of the lumbar region. 

F. The nerves of the sacral region. 

G. The nerves of the leg and foot. 



466 



NEUROLOGY. 



CRANIAL NERVES. 



iist set — to roof of nose. 
2nd set — to upper third of septum. 
3rd set — to superior and middle turbinated bones. 

2nd Cranial (Optic). . . . \ Retinal branches. 

f(i) Superior branch (to superior rectus and levator palpe- 
I brae). 

3rd Cranial (Motor J ( Internal rectus. 



OCULI). 



(2) Inferiw branch to \ Inferior rectus. 

( Inferior ob- \ Branch to ciliary 
lique. . . . ( ganglion. 



4th 
Cranial 



Trochlearis, 

or -j Supplies the superior oblique muscle 

Patheticus. . . 



5th Cranial 
(Trigeminus). 



Ophthalmic 
nerve. 



B. Superior 

MAXILLARY. 



C. Inferior 

MAXILLARY. 



r (i) Lachrymal branch. 

(2) Frontal j Supra-orbital nerve, 
branch. { Supra-trochlear nerve. 

Ganglionic nerve (to ciliary gan- 
glion). 
Long ciliary nerves. 
Infra-trochlear nerves. 

j To septum of 
" \ nose. 
Mucous membrane 
and integument of 
nose. 



(3) Nasal 
branch. 



Internal set . 

External 
set. 



In spheno- 
maxillary « 
fossa. 



Orbital or temporo-malar nerve. 
Spheno-palatine nerves (to Meck- 
el's ganglion). 

f Superficial den- 

~ . . j tal branches. 

Posterior den-^ dental 

tal nerve. ^ ranch es. 



In infra-or- 
bital can- \ Anterior dental nerve, 
al. 

i' Palpebral branches. 
Nasal branches. 
Labial branches. 

f (1) Masseteric branch. 

TFrom ante-) ^ ' ? ? '( Posterior. 
! rior trunk. ' (3) Buccal branch. 

{$ Pterygoid. | Exfemi. 



r (1) Auriculo-tem- j Auricular. 
I poral nerve. \ Temporal. 
From poste- \ (2) Gustatory nerve. 
rior trunk. j r My i hyoid. 

I (3) Inferior dental \ Incisor. 
I nerve. 1 Mental, 

t DentaL 



6th Cranial (Abducens). \ Supplies the external rectus muscle. 



THE CRANIAL NERVES. 



467 



7th Cranial (facial . . . . < 



f In the auditory canal. \ Branch to audit0I 7 
' ( nerve. 



Branches 
of commzt- < 
nication. 



In the aqueductus 
Eallopii. 



At its exit from the 
stylo-mastoid for- 
amen, with the fol- 
lowing nerves. 



I On the face. 



r Large petrosal (to 
Meckel's ganglion), 

Small petrosal (to Otic 
ganglion). 

External petrosal (to 
[_ meningeal plexus. 

Great auricular. 
Auriculo-temporal, 
Pneumogastric. 
Glosso-pharyngeal. 
^ Carotid plexus. 

\ Branches to 5 th nerve. 



Branches 



f In the aqueductus ( Tympanic nerve. 

Eallopii. \ Chorda-tympani nerve. 

f Posterior auricular 



»/ distri-l Near the stylo-mas- J nerve. 



bution. 



toid foramen, 
On the face. 



] Digastric branch. 
[ Stylo hyoid branch. 

Temporo-facial nerve. 
Cervico-facial nerve. 



8th Cranial (auditory). 



Vestibular branch . 



Cochlear branch.. 



Filaments to the utricle. 
Filaments to the saccule. 
Filaments to the ampullae. 

Cochlear plexus. 
Radiating fibres. 
Filaments to organ of Corti. 



9th Cranial (glosso- 
pharyngeal). 



"(i) Tympanic, or 
" Jacobson's 
net ve." 



r Communicating \ ™ *» P., s , a ' 

nelvesj Jo Cfoti* plexus. 

( Small petrosal. 

-r, r e j« m. • f Fenestra ovalis. 
Branches of distn- Fenestra rotun- 

bution to < , 

da. 

(2) Carotid branches. .. . • , [ Eustachian tube. 

(3) Pharyngeal branches (help to form pharyngeal plexus). 

(4) Muscular branches (to muscles of pharynx). 

(5) Tonsillar branches (help to form tonsillar plexus). 
^(6) Lingual branches. 



468 



NEUROLOGY. 



ioth Cranial. 
PNEUMOGASTRIC. 



f Integument of pinna. 

, s . . 7 L L | Ascending filaments (ioin facial 
r(l) Auricular branch , x & VJ 

/* i j> \ ~\ nerve). 

(Arnold s nerve). ,- -r>. i- ri *.'/•• 

v I Descending filaments (join auricu- 

la lar branch of the facial nerve). 

(2) Pharyngeal branches (help to form pharyngeal plexus). 



(3) Superior larynge 



AL | 



External laryngeal branch. 
Internal laryngeal branch. 



(4) Recurrent laryngeal f Supplies the muscles of pho- 
nerve \ nation. 

.,„,., , ( Cervical cardiac nerves. 

(=,) Cardiac branches ■{ --r? ■ j- 

KDJ ( 1 koracic cardiac nerves. 



,-x t, , , , ( Anterior pulmonary. 

(6) Pulmonary branches. . . } Posteno f pulmon J y , 



(7) (Esophageal branches. 

(8) Gastric branches. 

(9) Hepatic branches. 



nth Cranial (spinal 
accessory) 



r Branches to pharyngeal plexus. 
f Accessory portion (by 

means of sheath • Branches to superior laryngeal nerve. 

of pneumogastric^ Branches to recurrent laryngeal 
nerved) 



Branch to sterno-mastoid muscle. 
Branch to trapezius muscle. 

( 2nd cervical nerve. 
Spinal portion < Communicating 1 3rd cer vical nerve. 

branches to. ... | 4th cervical nerve. 
^5th cervical nerve. 



1 2th Cranial (hypo- 
glossal) 



nication. 



'To ganglion of the trunk of the 

pneumogastric. 

To superior cervical ganglion of the 
r Branches of commu- J sympathetic. 

To loop between the 1st and 2nd 
cervical nerves. 

I To the gustatory nerve. 

Descendens noni nerve. 
To thyro-hyoid muscle. 
To genio-hyoid muscle. 
To stylo-glossus muscle. 
To hyo-glossus muscle. 
To genio-hyo-glossus muscle. 
I To the substance of the tongue. 



Branches of distribu-^ 
Hon. 



SUMMARY OF CRANIAL NERVES. 460 



SUMMARY OF THE CRANIAL NERVES. 

The cranial nerves may be subdivided, according to the pe- 
culiar function of each, into four groups, which may be enum- 
erated as follows : 

A. B. 

Nerves of Special Sense. Nerves of Motion. 

Olfactory (smell). Motor oculi. 

Optic (sight). Patheticus or trochlears. 



Auditory (hearing). Part of third division of 5th. 

Part of glosso-pharyngeal. \ T . Abducens or 6th nerve. 

Gustatory branch of fifth ? ) Facial. 

Spinal accessory. 

Hypoglossal. 

C. D. 

Nerves of Common Sensation, Mixed Nerves. 

Fifth (greater portion). Pneumogastric. 
Part of glosso-pharyngeal. 



All of the cranial nerves possess what is called a superficial 
and a deep point of origin from the substance of the brain ; and all 
escape from one or more of the cranial foramina. 

In the preceding tables, both the points of origin and the 
foramina of escape have been omitted, since the first can best be 
memorized by arranging the point of origin of the twelve sepa- 
rate nerves together, and since the latter has already been fully 
given in a preceding table of the foramina of the skull and the 
parts contained in each r which will be found in the closing pages, 
descriptive of the skull in general. The deep points of origin of 
the cranial nerves will not be given in this work, since they are, 
at present, too much matters of dispute to allow of any positive 
or absolute statement. 



470 neurology. 

Apparent Origin of the Cranial Nerves. 

(i) Olfactory nerve From the olfactory bulbs. 

(2) Optjc nerve By the optic tracts, from the corpora quad- 

rigemhia. 

(3) Motor oculi nerve Front part of pons Varolii. 

(4) Trochlear nerve Upper part of valve of Vieussens. 

(5) Trifacial nerve Side of the pons Varolii. 

(6) Abducens nerve Corpus pyramidale, close to pons Varolii. 

(7) Facial nerve Lateral tract of medulla oblongata. 

(8) Auditory nerve Lineoz transversce of 4th ventricle. 

(9) Glosso-PHARYNGEAL nerve.. . . ... .Groove between olivary and restiform bodies 

in medulla oblongata. 

(10) Pneumogastric or vagus nerve. . . .Lateral tract of medulla oblongata. 

(11) Spinal accessory nerve Lateral tract of medulla oblongata and the 

spinal coj'd (to 5th cervical). 

(12) Hypoglossal nerve Groove between olivary and pyramidal 

bodies in medulla oblongata. 

The first pair of cranial nerves resemble the nerves of the 
sympathetic system, since they are small in size, soft in texture, 
and destitute of the white substance of Schwann. The olfactory 
tracts, by some anatomists, are described as a part of the olfac- 
tory nerve. 

The second pair of cranial nerves are each pierced by the arteria 
centralis retinae, and are distributed to one of the layers of the 
retina. An association of an important character exists between 
these nerves and the third pair of nerves, which regulates the adap- 
tation of the pupil to the amount of light required by the eye. 

The third pair of nerves, from their association with the ciliary 
ganglia of the orbits, control the contraction of the pupils, in ad- 
dition to being the great motor nerves of the muscles of each 
eyeball. 

The first four pairs of cranial nerves, in addition to the first 
branch of the fifth pair (ophthalmic nerve), have -important relations 
within the cavernous sinus, before their exit from the cranial cav- 
ity ; and they bear relations also with each other, both during their 
passage through and after their exit from the sphenoidal fissure, 
and subsequently within the orbit. 

The nerves which go to the orbit comprise the 2nd, 3d and 4th 
cranial nerves, the ophthalmic branch of the 5th, the orbital 
branches of the superior maxillary nerve and of Meckel's gang- 
lion, and the 6th nerve. Some of these nerves have important 
relations in one or all of the three following situations: I. In 
the cavernous sinus. 2. In the sphenoidal fissure. 3. In the 
cavity of the orbit itself. 



SUMMARY OF CRANIAL NERVES. 



471 



The relations in the cavernous sinus will be found in the de- 
scription of that sinus, in the chapter upon the veins. 

In the sphenoidal fissure, the 4th nerve, and two branches of 
the ophthalmic pass above the external rectus muscle of the eye, 
viz., the frontal and lachrymal branches ; while four nerves pass 
between the two heads of that muscle, in the following order from 
above downwards ; viz., the superior division of the 3d nerve, the 
nasal branch of the ophthalmic nerve, the lower division of 3d 
and the 6th nerve. 

In the orbit, three nerves lie above the muscles in close contact 
with the periosteum, viz., the ones which pass above the external 
rectus muscle, in the sphenoidal fissure ; and the other four nerves 
lie in the same order from above downwards in the orbit, as they 
did between the two heads of that muscle. 

Each of the FIFTH PAIR of nerves after its exit from the skull, 
has connected with it four ganglia of the sympathetic system ; 
each of which receives a motor, a sensory, and a sympathetic nerve 
filament, and which gives off subsequent branches of distribution. 
These ganglia are called the ciliary ganglion (ophthalmic or len- 
ticular), the spheno-palatine or Meckel's ganglion, the Otic gang- 
lion, and the submaxillary ganglion. The formation and distri- 
bution of each of these ganglia is as follows. 

Ciliary Ganglion. 

This ganglion is often called the ophthalmic ganglion, from its 
relation with the ophthalmic artery and nerve, and the lenticular 
ganglion, from its shape. It is the size of a pin's head, and is 
situated at the back of the orbit, upon the outer side of the optic 
nerve. 

Its sensory root arises from the nasal branch of the ophthalmic. 

Its motor root arises from the third cranial nerve. 

Its sympathetic root arises from the cavernous plexus. 

Its branches are distributed to the ciliary muscle and the iris. 

Meckel's Ganglion. 

This ganglion, called the spheno-palatine ganglion, is con- 
nected with the second division of the fifth pair of cranial nerves. 
It. is situated in the spheno-maxillary fossa, and is of large size. 

Its sensory root arises from the superior maxillary nerve. 

Its motor root is derived from the Vidian nerve (by means of a 
branch of the facial). 

Its sympathetic root is derived from the carotid plexus. 

The two latter roots of Meckel's ganglion are both conveyed 
to it by means of the Vidian nerve, which, in reality consists of 



472 



NEUROLOGY, 



carotid filaments and the large petrosal branch of the facial 
nerve. 

The brandies of distribution of * Meckel's ganglion are as 
follows : 

By its anterior palatine branch, to the hard palate and nares. 

By its posterior palatine branch, to the tonsils and soft palate. 

By its superior nasal branch, to the nares and antrum. 

By its naso-palatine branch, to the roof of the nose, the septum, 
and the hard palate. 

By its pterygopalatine branch, to the mucous membrane of the 
pharynx. 

Otic Gaxgliox. 

This ganglion is situated on the inferior maxillary nerve, just 
below the foramen ovale. 

Its sensory root arises from the auriculo-temporal nerve. 
Its motor root arises from the internal pterygoid nerve. 
Its sympathetic root springs from a plexus on the middle men- 
ingeal artery. 
Its branches of distribution supply the tensor palati and the 
tensor tympani muscles. 

Submaxillary Gaxgliox. 

This ganglion is situated between the gustatory nerve and 
the submaxillary gland. It is about the size of a pin's head. 

Its sensory root arises from the gustatory nerve. 

Its motor root arises from the chorda tympani nerve. 

Its sympathetic root arises from a plexus around the facial 
artery. 

Its brandies of distribution supply the submaxillary gland and 
its duct. 

The fifth nerve, before its division into branches, has devel- 
oped upon its sensory portion a swelling, called the Gasserian 
ganglion, which is crescentic in shape, and which is situated at the 
apex of the petrous portion of the temporal bone. 

The superior maxillary division of the fifth nerve passes, 
through the foramen rotundum, into the spheno-maxillary fossa, 
then into the infra-orbital canal, then through the infra orbital 
foramen, upon the face. It is thus divided into three distinct 
portions, from each of which branches are given off, as shown on 
page 466 of this work. 

The inferior maxillary division of the fifth nerve joins, after 
its exit through the foramen ovale, with the motor root of that 
nerve, and thus becomes both a motor and a sensory nerve. 



SUMMARY OF CRANIAL NERVES. 



473 



The auriculo-temporal nerve is pierced by the middle menin- 
geal artery. 

The FACIAL nerve, as is represented in the table of its branches, 
on page 467, pursues a very indirect course. It passes successively 
through the internal auditory canal, the aqueductus Fallopii, the 
stylo-mastoid foramen, and is then distributed upon the face. 
In each of these four portions, it gives off branches, some of which 
are of great importance. The facial nerve supplies all the mus- 
cles of expression. 

The large petrosal branch escapes into the cranium through 
the hiatus Fallopii; it then passes out of the skull, through the 
foramen lacerum medium ; then unites with filaments of the caro- 
tid plexus to become the Vidian nerve ; and then passes through 
the Vidian canal to join with Meckel's ganglion. 

The chorda tympani nerve passes first through a canal, parallel 
with the aqueductus Fallopii ; it then enters the tympanum 
through the iter chordae posterius ; then runs along the upper 
border of the drum membrane of the ear ; then enters the iter 
chordae anterius, then passes through the canal of Huguier ; then 
joins the gustatory nerve, between the two pterygoid muscles ; 
and is subsequently distributed to the lingualis muscle and the 
submaxillary gland. By some authorities, the origin of this nerve 
is traced to a filament called the portio intermedia, or the nerve 
of Wrisberg. 

This nerve is now supposed to give to the gustatory nerve 
the power of appreciati?ig taste, and for that reason is classed by 
some as a nerve of special sense. 

The GLOSSO-PHARYNGEAL nerve gives the sense of taste to 
the posterior third of the tongue. Its tympanic branch is called 
Jacobsons nerve and is distributed to the internal structures of 
the ear. This nerve has tivo gaiiglia developed upon it, one of 
which is called the ganglion of A ndersch, and the other the jugular 
ganglion. 

The PNEUMOGASTRIC nerve, called also the vagus nerve, is one 
of the most important nerves in the human body. In the neck, 
it bears an intimate relation to the internal and common carotid 
arteries and to the internal jugular vein ; by its laryngeal branches, 
it controls the muscles of voice ; by its cardiac branches, it exerts 
a powerful influence over the heart's action ; by its pulmonary 
branches, it becomes the great excitory nerve of respiration; 
while, by its gastric and hepatic branches, it exerts some influ- 
ence upon the digestive functions. It has two ganglia upon it, 
one in, and one below the jugular foramen, which are called, re- 



474 



NEUROLOGY. 



spectively, the jugular ganglion or the ganglion of the root, and 
the inferior ganglion or the ganglion of the trunk. 

The recurrent laryngeal nerve, so called because it winds 
around the subclavian artery upon the right side, and, upon the 
left side, around the aorta, before it ascends to the larynx, is the 
great nerve of phonation. It is said to consist principally of 
fibres derived from the spinal accessory nerve, which have simply 
used the sheath of the pneumogastric nerve for protection, during 
their course through the neck. 

The SPINAL ACCESSORY nerve, by its branches of communica- 
tion with the pneumogastric nerve, as above mentioned, gives 
origin, through fibres derived from its accessory portion, to the 
two nerves of phonation. The fibres derived from its spinal por- 
tion are mostly distributed to muscles and the cervical nerves of 
the upper portion of the neck. 

This nerve has been often called the " superior respiratory 
nerve of Bell" since it affords the motor power to the muscles 
which open the glottis, previous to each inspiration, and thus it 
allows air to enter the lung without impediment. 

The HYPOGLOSSAL nerve gives off only one branch which 
possesses any surgical interest, viz., the descendens noni nerve, 
which descends in front of the sheath of the common carotid 
artery, and communicates with the communicans noni nerve, a 
branch derived from the cervical plexus. 



NERVES OF THE CERVICAL REGION. 



47S 



NERVES OF THE CERVICAL REGION. 



1ST Cervical Nerve 

{Sub-occipital) . . 



Posterior division. 



Anterior division. 



'Branch to posterior division of 2nd 

cervical. 
Branches to the posterior cranio-verte- 

bral set of muscles. 
Branch to complexus muscles. 
Branch to integument of occiput. 

Branch to rectus cap. ant. major. 
Branch to rectus cap. ant. minor. 
Branch to rectus cap. lateralis. 

{ 2nd Cervical. 

~ • ,. Pneumogastric. 

Communicating TT , & , 

branches tol Hypoglossal. 

Superior cervical 
ganglion. 



Posterior division 
(very large \xi\ 
size). 



2nd Cervical Nerve 



f Splenius. 
Cervicalis ascend- 
' External branch] ens. 

(Supplying). . j Transversalis colli 
I Trachelo-mastoid. 
|^ Complexus. 



Anterior divisi< 



Internal branch 
{Great oca 
net ve. 



f Joins with 1st 
cinuii. j cervical nerve. 
ipital \ Supplies integu- 
ment of occiput 

( as far as vertex. 



f Filament to sterno-mastoid. 
j Ascending branch (to ist cervical nerve) 
I Descending branch(to 3d cervical nerve) 
j Filament to communicans noni nerve. 
Small occipital nerve (occipitalis mi- 
[ nor). 



f Posterior division.^ 



External branch 



f Splenius. 

I Cervicalis ascend- 



(Supplying).. I 



eus. 
Transversalis colli 
[_ Trachelo-mastoid. 



Internal branch. \ Integument of oc- 
(Supplying). . \ ciput. 



-Anterior division. 



Ascending 

branches. 



Descending 

branches. 



Auricularis mag. 
nus. 

Supt • rficii r I cervical 

Branch to second 
cervical nerve. 

Branch to the spi- 
nal accessory. 

f Filament to fourth 
nerve. 
Filament to leva 
tor anguli scap- 
ulae. 



476 



NEUROLOGY. 



4th Cervical Nerve, 



'Posterior division., .(distributed to muscles of the back). 

r Filament to 3rd cervical nerve. 

I Filament to 5th cervical nerve. 
__ Anterior division..^ Filament to phrenic nerve. 

\ Filament to scalenus medius. 



Filaments to szipra-clavicular 



Anterior 

branch of 1st 

Cervical 

nerve. 

Anterior 

branch of 2D 

Cervical 

nerve. 

Anterior 

branch of 3D 

Cervical 

nerve. 

Anterior 
branch of 
4th Cervi- 
cal nerve. 



CERVICAL PLEXUS OF NERVES. 



Superficial f Ascending 

BRANCHES. | Set. 

(integument- \ 
ary). 



Descending 



Occipitalis minor. 
Auricularis magnus. 
Superficialis colli. 

Supra- clavicular branches. 



CERVI- 
CAL 

PLEXUS, 



Deep 



BRANCHES. 



Internal 



Communicating. 

fRect. cap 
major 

Muscular 



ant. 
ant. 



set. 



alis, 

Com jnuni cans noni. 
_ Phrenic. 



Rect. cap 

minor. 
Rect. cap. later 



f Muscular- 



External 

set.1 



' Sterno-mastoid. 

Levator anguli 
scap. 

Trapezius. 
t Scalenus med. 



. Communicating. 



SUMMARY OF THE CERVICAL NERVES. 

The posterior division of each of the cervical nerves as shown 
in the preceding tables, are principally distributed to muscles and 
have no special names, with the exception of one branch which is 
derived from the second cervical nerve, and which is called the 
great occipital nerve. 

The anterior divisions of the first four cervical nerves, however, 
enter into the formation of the cervical plexus, while those of the 
lower four cervical nerves enter into the formation of the brachial 
plexus, which is not shown in the preceding tables, since the dis- 
tribution of the latter plexus causes it to be more properly classed 
among the nerves of the upper extremity. 

It will be seen by reference to the preceding table that the 
cervical plexus is first subdivided into branches which lie near the 
surface and those more deeply placed ; that the superficial set 



THE CERVICAL NERVES. 477 

comprise three nerves which supply the integument, and which pass 
upwards towards the head ; and one nerve with its branches which 
descends upon the clavicle. The deep branches are also divided 
into two sets, four being called internal branches, since they pass 
towards the median line of the body, and two being called ex- 
ternal branches, since they pass away from the median line. 

Of these ten nerve trunks given off from this cervical plexus, 
the PHRENIC NERVE is the most important. This nerve arises by 
three heads, derived from the 3rd, 4th and 5th cervical nerves, 
and descends along the inner aspect of the chest, being situated 
in the middle mediastinum, and is principally distributed to the 
diaphragm. It was named by Sir Charles Bell, and s still often 
called the internal respiratory nerve, since it passes internal to the 
chest wall. This nerve bears important relations to the subcla- 
vian artery, in the first and second portions of that vessel, and 
therefore possesses great surgical importance. Below the dia- 
phragm, the phrenic nerves assist to form some of the plexuses 
of the sympathetic. 

The comunicans noni nerve also possesses surgical importance 
since it joins with the descendens noni nerve and ramifies on the 
front part of the sheath of the common carotid artery. 

The rest of the branches of the cervical plexus are distributed 
either to muscles or the integument, or act as branches of com- 
munication to other nerves. 

The cervical plexus of nerves lies beneath the sterno-mastoid 
muscle, and in front of the levator anguli scapulae and the scalenus 
medius muscles. 



478 



NEUROLOGY. 



NERVES OF THE UPPER EXTREMITY, 
THE BRACHIAL PLEXUS. 



Anterior " 




division of 




5th Cer- 




vical 




nerve. 




Anterior 




division of 


From 


6th Cer- 


. outer 


vical 


cord of 


nerve. 




Anterior 




division of 




7TH Cer- 




vical 




nerve. 





Anterior ' 
division of 
8th Cer- 
vical 
nerve. 



Anterior 
division of 
ist Dor- 
sal nerve. 



From in- 
ner cord 
of 



BRACHIAL -1 
PLEXUS. 



Branches 
above the • 
clavicle 



'Posterior thoracic {external respira- 
tory nerve of Bell). 

Supra-scapu- j Supra-spinatus. 

■F ] Infra-spmatus. 

( Shoulder joint. 

'Rhomboidei muscles 
Subclavius. 
Muscular.. (8) ^ Scaleui muscles. 
v ' Longus colli. 

Levator anguli scap- 
ulae. 



t 



_ Communicating (to phrenic nerve). 



f Internal anterior 

thoracic. 
| Internal cutaneous, 
j Lesser internal cu- 
\ taneous (Wris- 
berg's nerve). 
Inner head of medi- 
an nerve. 
Ulnar nerve. 



Branches 
below the 
[clavicle. 



From inner 
cord 



From outer 
cord 



' External a n t e ri o r 
thoracic. 

External cutaneous. 

Outer head of me- 
dian nerve. 



f 1st subscapular nerve 

-rp a, . . 2d subscapular nerve 
r rom * poste- j ■. r n 

r.7.r-A \ 3^ subscapular nerve 
| Musculo-spiral nerve 
(^Circumflex, neive. 



riot cord, 



* The posterior cord of the brachial plexus is formed by a branch from both the 
inner and outer cord. 



NERVES OE UPPER EXTREMITY. 



479 



BRANCHES OF THE BRACHIAL PLEXUS. 
OUTER CORD. 



Branches of 

the OUTER 

cord of the" 

Brachial 

Plexus. 



(i) External C 
anterior tho- < Pectoralis major. 
racic. ( 



(2) External 
or musculo cu-K 

TANEOUS. 



r Integument of the front of forearm. 
Anterior 
branch. \ Integument of ball of thumb. 

t Joins with the radial nerve. 



Posterior 
branch. 



(3) Median. 



In the 
hand. 



In fore- 
arm. 



Integument of radial side of back of forearm 
Joins with the radial nerve. 
Joins with the external cutaneous branch of 
the musculo-spiral. 

f Pronator radii teres, 
j Flexor carpi radialis. 
Muscular. • • <j Palmaris longus . 

! Flexor sublimis digitorum. 



Anterior 
Interosseous. 



Flexor longus pollicis. 
Flexor profundus digitorum 
Pronator quadratus. 



. Integument of palm. 
Palmar Cuta- J lnt mi f baU f th 
^ neous. J d 

1 thumb. 



'External 

Branch. 



Internal 

Branch. 



Abductor pollicis. 
Opponens pollicis. 
Flexor brevis pollicis (outer 

head). 
Digital to thumb. 
L Digital to index finger. 

'Digital to contiguous sides 
of index, middle, and ring 
fingers. 

Filaments to the two outer 
lumbricales muscles. 



480 



NEUROLOGY 



BRANCHES OF THE BRACHIAL PLEXUS. 
INNER CORD. 



Branches of 

the INNER 

CORD of the 

Brachial 

Plexus. 



(i) Internal f 
anterior tho- -j Both Pectoral muscles. 
racic. ( 



(2) Internal J 



CUTANEOUS. 



f Anterior j Integument of the anterior surface of the in- 
branch. \ ner side of the forearm as low as the wrist. 

I Posterior j Integument of the posterior surface of the in- 
L branch. ( ner side of the forearm to near the wrist. 



(3) Lesser in- f 
ternal cuta- I Integument of the posterior surface of the lower third 
neous. (Wris- I of the arm. 
berg.) t 



r Articular (to elbow joint). 



In the 
forearm. 



(4) Ulnar, j 



Muscular. 



Palmar cuta- 
neous. 

Dorsal cuta- 
neous. 



i Flexor carpi ulnaris. 

•< Inner half of flexor profun- 

( dus digiiorum. 

Integument of front of wrist 
and palm of hand. 

f Integument at back of wrist 
j and i-^ fingers on inner 
I side of dorsal surface of 

L hand. 



Articular. . . . -( To wrist joint. 



I 

^In hand. 



f Superficial 

branches. 



Deep 
L branches. 



Palmaris brevis. 
Integument of inner \\ fin- 
gers on palm. 

f Muscles of little finger. 
Interossei muscles. 
The two inner lumbricales. 
Adductor pollicis. 
Flexor brevis pollicis (in- 
ner head). 



NERVES OF UPPER EXTREMITY. 



481 



BRANCHES OF THE BRACHIAL PLEXUS. 
POSTERIOR CORD. 



Branches of 
the POSTE- 
RIOR CORD^ 

of the 



(i)SUBSCAPULAR 
NERVES. 



The 

upper 
or 1st. 

The lont 



•{Subscapular muscle. 



or 2nd, 



f < Latissimus dorsi. 



The low- 
er or 



I 

low- ( rr 

n , < Teres major. 



(2) Circumflex \ 



Superior ( Deltoid, 
branch. \ Integument over the shoulder. 



J Inferior 
I branch, 



{Teres minor. 
Deltoid (posterior portion). 
Integument over the shoulder. 



Brachial 
Plexus. 



(3) Musculo- 

SPIRAL. 



f Triceps. 
Mus- I Anconeus. 
cular X Brachialis anticus. 
branches j Supinator longus. 

[ Extensor carpi radialis longior. 



Cutane- 



Integument of the inner and posterior por- 
tions and the outer and anterior portion 

OUS > r r 

, , I of arm. 

ranc es j^ j n t e g Umen f f th e outer aspect of the forearm 



f Integument of outer side of 
External thumb. 

branch, j Integument of ball of the 
I thumb. 



Radial. 



Posteri- 
or IN- 
TEROS 
SEOUS. 



Internal 



branch. 



{Integument of 3^ fingers on 
radial side of dorsum of 
hand. 



'All muscles on back (Anconeus. 

of forearm except ■< Supinator longus. 
three ( Ext. carp. rad. long. 

L Filaments to wrist joint. 



482 NEUROLOGY. 



SUMMARY OF THE NERVES OF THE UPPER EX- 
TREMITY. 

The BRACHIAL PLEXUS consists of three cords, called the outer 
cord, the inner cord, and the posterior cord. The outer and inner 
cords are formed directly by the anterior branches of the spinal 
nerves, while the posterior cord is formed independently of the 
spinal nerves, by a branch given off from each of the other two 
cords. This plexus of nerves lies between the scalenus anticus 
and the scalenus medius muscles, and is very broad at its com- 
mencement, but becomes constricted as it enters the arm. 

The brachial plexus of nerves bear an important surgical rela- 
tion to the second and third portions of each subclavian artery, 
and to the first and second portions of each axillary artery. 
The third portion of each axillary artery bears relation to its 
branches, but not to its main cords. 

The brachial plexus, within the neck, is pierced by the trans- 
versalis colli artery. The following branches of special import- 
ance are given off above the line of the clavicle. 

1. A communiating branch, which completes the phrenic 

nerve. 

2. The posterior thoracic nerve, which arises by two heads, one 

from the fifth and one from the sixth cervical nerves, 

and which is distributed to the serratus magnus muscle. 

Since it assists inspiration, and as it passes down 

upon the external aspect of the chest, it is frequently 

called the " external respiratory nerve of Bell." 

The brachial plexus of nerves, below the level of the clavicle, 

lies to the outside of the first portion of the axillary artery, while 

in the second portion of that vessel, its three cords surround it, 

and, in the third portion of that vessel, the branches of each of 

the three cords bear a relation to the artery. 

The MEDIAN NERVE is the most important branch of the 
outer cord, and bears relations with the brachial artery, in the 
arm and at the bend of the elbow. It passes between the two 
heads of the pronator radii teres muscle, and is distributed, in the 
ihand, to the integument of the outer three fingers and half of tlie 
palm. The muscles supplied by this nerve are shown on page 
479 of this volume, and also in a table inserted in the chapter on 
myology. 



NERVES OF UPPER EXTREMITY. 483 

The ULNAR NERVE is the most important branch of the inner 
cord of the brachial plexus. It bears an important relation to 
ths elbow-joint at the inner condyle of the humerus, where it 
passes between the two heads of the flexor carpi ulnaris muscle. 
It is frequently jarred by blows, in that vicinity, giving the sensa- 
tion, called "injury to the funny bone." In the incision of the 
elbow-joint, this nerve has particularly to be avoided. It sup- 
plies the elbow and wrist joints, and the integument of the internal 
one and a half fingers, on both the palmar and the dorsal surf ace 
of the hand. 

The muscles supplied by this nerve are shown on page 480 
of this volume, and in a previous table under myology. 

The MUSCULO-CUTANEOUS NERVE pierces the coraco-brachia- 
lis muscle and is often called, for that reason, the "perforans 
Casserii." 

The CIRCUMFLEX NERVE is an important branch of the pos- 
terior cord of the brachial plexus and supplies the shoulder-joint, 
thexleltoid and teres minor muscles, and the integument of the 
shoulder. It accompanies the posterior circumflex vessels. 

The MUSCULO-SPIRAL NERVE arises from the posterior cord of 
the brachial plexus, and is the largest branch of that plexus. At 
the external condyle of the humerus, which it reaches by passing 
around that bone in the spiral groove, it divides into two nerves 
called the radial and the posterior interosseous nerves. Before 
its division, it supplies two muscles of the arm and three of the 
forearm, and the integument of portions of both the arm and 
forearm. 

The RADIAL NERVE, a branch of the musculo-spiral nerve, lies 
on the outer side of the radial artery and in close relation to it in 
the middle portion of the forearm. It supplies the outer side 
and the ball of the thumb, and the integument of the outer three 
and a half of fingers, upon the back of the hand. 

The POSTERIOR INTEROSSEOUS NERVE, a branch of the mus- 
culo-spiral, supplies all the muscles on the back of the forearm, ex- 
cepting the three which are supplied by the musculo-spiral before 
this nerve was given off. It also sends a filament to the wrist- 
joint. 



4§4 



NEUROLOGY. 






NERVES OF THE DORSAL REGION. 



External 
branches 



DORSAL 

NERVES. 



Posterior 
visions. 



Di- 



Intemal 
^branches 



r Filaments to transversalis colli. 
Filaments to longissimus dorsi. 
In upper! Filaments to trachelo-mastoid. 



6 nerves. 



Filaments to levatorescostarum. 
Filaments to sacro-lumbalis. 
L Filaments to accessorius. 



In the ( Same muscles as in preceding 
lower six ■< bracket. 
nerves. ( Integument of the back. 



In upper ( Filaments to semispinals dorsi. 
six •< Filaments to multifidus spinse. 
nerves. ( Integument of back. 



In lower ( Same muscles as in preceding 
six \ bracket, 
nerves. ( No cutaneous filaments. 



Six 
upper or 
thoracic -l 
intercost- 
als. 



'Muscular \ Intercostals. 
branches \ Triangularis sterni. 

Lateral f ^ nte S ument °f chest and mam- 
mae. 



cutane 
ous. 

Anterior 
cutane- 
ous. 



| Upper part of external oblique 
[_ muscle. 

Integtwient over upper part of 
latissimus dorsi and the 
scapular region. 



Anterior Di-. 
visions. 



Six 
lower or 
thoracico- 
abdomin 
al inter- 
costals. 



Muscular ( Intercostals. 
branches \ Abdominal muscles. 

(Integument of abdomen, as far 
Lateral J as the edge of rectus. 
\ cutaneous \ Integument over lower part of 
^ latissimus dorsi. 

Anterior j U PP er P art f "ctus and integ- 
cutaneous \ umeni m front P art of abdo " 



THE DORSAL NERVES. 485 



SUMMARY OF THE NERVES OF THE DORSAL 

REGION. 

In the preceding table, which illustrates the distribution of 
the nerves of the dorsal region, it will be perceived that the 
largest proportion of the branches are distributed to the muscles 
of the back, the muscles of the abdomen, and the integument of 
the trunk in general. The integumentary distribution of special 
nerves is rapidly assuming a great practical importance, since, 
by a thorough knowledge of these branches, lesions of nerve 
trunks and of the spinal cord itself can often be localized with 
precision. 

The posterior divisions of the dprsal nerves are distributed to 
the muscles and integument, chiefly of the back ; while the anterior 
divisions of the dorsal nerves are distributed to the thoracic and 
abdominal muscles and to the integument of the various regions 
of the chest and abdomen. 

The first intercostal nerve enters almost entirely into the 
formation of the brachial plexus ; but it gives off also an inter- 
costal branch which runs along the first intercostal space and 
terminates at the front part of the thorax. 

The lateral cutaneous branch of the second intercostal nerve, 
perforates the second intercostal space and is called the intercostol- 
humeral nerve. It either joins with the nerve of Wrisberg, after 
crossing the axillary space, or it supplies the place of that nerve 
in case it be wanting. 



486 



NEUROLOGY. 



NERVES OF THE LUMBAR REGION. 



LUMBAR 

NERVES. 1 



Posterior 



divisions. 



r isx Lumbar 
nerve. 



2nd Lumbar 
nerve. 




f Filaments to erector spinae muscle. 
External \ Filaments to intertransversales. 
branches. j Filaments to integument of back part 

(_ of gluteal region. 



Internal 
branches. 



3rd Lumbar h 
nerve. 



4th Lumbar 
nerve. 



Lumbar 
Plexus. 



(Fi 

i Fi 



Filaments to multifidus spina? muscle 
Filaments to integument near spinal 
column. 



Ilio-hypogastric 

nerve 
Ilio-inguinal nerve 
Communicating to 



Given of 

e 'J the is 

* J TTTMBA 



2nd lumbar. 



off by 

ST 

lumbar 
nerve. 



Genito-crural nerve. ( Q[ wen ff |™ 

External cutaneous I ,, „„^ ^ 
/ the 2ND 
nerve. < 

~ ■'■ . | LUMBAR 



Part of anterior 

crural nerve. 
Part of obturator j Given off by 
nerve, j the 3RD 



Part of accessory 

obturator nerve. | 
Communicating to 

4th lumbar. [_ 

Part of anterior f 

crural nerve, j 
Part of obturator 

nerve. ■{ 
Part of accessory 

obturator nerve 
Lumbo-sacral cord. 



LUMBAR 
NERVE. 



Given off by 

the 4TH 

LUMBAR 
NERVE. 



In this table, the formation of the lumbar plexus is shown, as 
well as the branches which are given off from each nerve which 
assists to form it. 

It will be perceived that three important nerves, viz., the 
anterior crural, the obturator, and accessory obturator nerves, are 
formed by branches both of the 3d and 4th lumbar nerves, and 
therefore may be said to arise by two heads. The accessory obtu- 
rator nerve, however, arises occasionally by a branch derived only 
from the 4th lumbar nerve ; its other head being a branch given 
off from the obturator nerve. 



THE LUMBAR NERVES. 



487 



DISTRIBUTION OF THE BRANCHES OF THE LUM- 
BAR PLEXUS. 






LUMBAR 
PLEXUS. 



{Iliac branch. \ Integument of gluteal region. 
Hypogastric 

branch. 



Integument of the hypogastric region. 



(2) Ilioin- 
guinal. 



(3) Gen 1 TO- 
CRURAL. 



(4) External 
cutaneous. 



r Internal oblique muscle. 

Integument of upper and inner portion of thigh. 

Integmuent of scrotum. 

Integument of penis. 
^Integument of labium. 

^ . . j ( Cremaster muscle. 

branch | Scrotum - 

* ( Round ligament of female. 

Crural branch \ Inte §^nt of the front and upper portion 
( 01 the tnign. 

Anterior j Integument on the anterior and outer as- 

branch. \ pect of thigh, as low as the knee. 



Posterior 



(5) Anterior 
crural. 



( Integument of the posterior and outer as- 
branch. \ pect of the thigh. 



f The sartorius muscle. 
Middle cuta- J Integument of anterior as- 
neous nerve \ pect of thigh, as low as 
(__ the knee. 



(Integument of 
External J inner and 
branch, j outer sides 
(_ of knee. 

C Integument of 
Posterior) inner sides 
branch. 1 of the thigh 

[_ and the leg. 



Anterior 

division. 



Internal 
cutaneous 
nerve. 



Long or inter- 
nal saphe 
[_ nous nerve 



- ( Integu, 

- < and 
. ( sides 



gument of knee joint 
front and inner 
of the leg and foot 



Posterior 

division, 



f Muscular 

branches. 

I 
[Articular 

branches. 



All the muscles on front 
of thigh except the ten- 
sor vagina fetnoris and 
the sartorius. 

Two in number. Dis- 
tributed to capsule of 
knee-joint. 



488 



NEUROLOGY. 



BRANCHES OF LUMBAR PLEXUS. 
Continued. 



' (6) Obtura- 
rator nerve 



LUMBAR 
PLEXUS. - 
(continued) 



Anterior 

branch. 



Articular ( ^ , . , . . , 

branches. ]^ h^yotnt. 



f To gracilis. 
Muscular J To adductor longus. 
branches. | To pectin eus. 

[_ To adductor brevis. 



Posterior 

branch. 



Anastomotic 
branches. 



Articular 



With internal cutaneous 

nerve. 
With internal saphenous 

nerve. 



branches. \^ knee-joint 

Muscular j Obturator externus. 

branches. ( Adductor magnus. 



(7) Accessory obturator h 
nerve 



Muscular ( ^ 

branch. \ To P ectin eus. 

Articular ) ^ , . . . . , 

branches. \^ ^p -joint. 



Cutaneous 
branches. 



( To the integument of 



thigh and leg. 



SUM MAR Y OF L UMBAR NER VES. 489 



SUMMARY OF THE NERVES OF THE LUMBAR 

REGION. 

In the preceding tables, which illustrate the distribution of 
the nerves of the lumbar region, it will be perceived that the 
posterior divisions of the lumbar nerves are of little importance 
as compared with the anterior divisions. 

The LUMBAR PLEXUS of nerves is formed from the anterior 
division of the first four lumbar nerves, each one of which nerves 
gives off, in addition to a communicating branch, some special 
branches of its own, which are included among the various 
branches of the lumbar plexus. 

This plexus is situated in the substance of the psoas magnus 
muscle. 

The ANTERIOR CRURAL NERVE arises by two heads from the 
3rd and 4th lumbar nerves. It bears an important relation, in 
Scarpa's space, with the femoral artery and its accompanying 
vein ; since all three pass underneath Poupart's ligament. It 
sends an articular branch to the knee-joint. 

The OBTURATOR NERVE arises by two heads, derived respec- 
tively from the 3rd and 4th lumbar nerves, and, after its exit from 
the pelvis, bears an intimate relation with the capsular ligament 
of the hip-joint, to which joint, as well as to the knee, it sends 
articular filaments. It is on account of this nerve, whose distri- 
bution to two joints has been mentioned, that disease of the hip- 
joint frequently manifests itself, in its early stages, by pain within 
the knee. 

The accessory obturator nerve, if it exists, usually arises by 
two heads derived from the 4th lumbar and the obturator nerves. 
It sends a filament to the hip-joint. 



490 



NEUROLOGY. 



NERVES OF THE SACRAL REGION. 



r External 

branches. 



Posterior 
divisions. 



SACRAL 

NERVES. 



Form anastomotic loops on back part of 
sacrum and on the posterior aspect of 
the great sacro-sciatic ligament. 

Terminate in cutaneous branches in the 
gluteal region. 



f Are distributed to the multifidus spinae 
'[_ Internal J muscle. 

branches. ] The back part of the coccyx is supplied 
(_ by the lower two nerves. 



Anterior 
divisions. 



Lumbo-sacral 
cord. 



ist Sacral 

nerve. 



2nd Sacral 

nerve. 



3RD bACRAL 

nerve. 



Part of 4TH Sa- 
cral nerve. 



'(i) Superior gluteal 
nerve. 



(2) Muscular branches. 



SACRAL 

\ PLEXUS. <( 



(3) Small sciatic nerve. 



(4) Great sciatic nerve. 



(S) PUDIC NERVE. 



THE SACRAL NERVES. 



491 



DISTRIBUTION OF THE BRANCHES OF THE 
•SACRAL PLEXUS. 



SACRAL 
PLEXUS 



Superior 
gluteal. 



Muscular 
branches. 



Superior branch 



(_ Inferior branch, 



Gluteus medius muscle. 
Gluteus minimus muscle. 

( Gluteus medius muscle. 
< Gluteus minimus muscle. 
( Tensor vaginae femoris. 



[ Pyriformis. 
J Obturator internus. 
■I Gemellus superior. 
I Gemellus inferior. 
[Quadratus femoris 



Articular \ Tohijoint 
branches. 1 r J 



Small 
sciatic. 



[Inferior gluteal ( ^, , . . 

branch \ Gluteus maximus muscle. 

[Integument of perineum. 
Inferior ftuden- \ Integument of upper and inner part of 
dal branch. | the thigh. 

[^Integument of scrotum or labium. 

Integument over gluteus 
maximus muscle. 



Cutaneous ; 

branch . ) 



f Ascending. 



[Descending. •< 



( Integument of inner and 



outer sides of posterior 
aspect of the thigh. 



Great 
sciatic. 



Articular (to hip-joint.) 

[ Adductor magnus. 
J Semimembranosus. 
] Semitendinosus. 
[_ Biceps flexor cruris. 



Muscular. 



[_ Terminal. 



External popliteal. 
Internal popliteal. 



'Perineal. 



PUDIC 

NERVE. 



perineal. 
[_ Muscular 
Inferior hemorrhoidal. 



[Cutaneous or [Integument of anal region, 

j superficial -j scrotum, penis and labia. 



(Sphincter ani muscle. 
\ Muscles of the perineum. 



Dorsal nerve of 
fienis. 



Integument of the dorsum and sides of 

penis. 
Branch to corpora cavernosa. 



492 



NEUROLOGY. 



SUMMARY OF THE NERVES OF THE SACRAL 

REGION. 

The SACRAL PLEXUS is seen, in the preceding tables, to be 
formed by the four upper sacral nerves, and, in addition, by the 
lumbosacral cord. It is triangular in shape and rests upon the 
pyriformis muscle. It is covered by the pelvic fascia and the two 
terminal branches of the anterior trunk of the internal iliac 
artery. 

The lumbosacral cord, which by some is not included in the 
sacral plexus of nerves, gives origin to the superior gluteal nerve, 
which, for that reason, is occasionally omitted from the branches 
of the sacral plexus. 

The SUPERIOR GLUTEAL NERVE accompanies the gluteal ves- 
sels through the upper part of the great sacrosciatic foramen, and 
in this situation, lies above the pyriformis muscle. Its branches 
are shown in a preceding table. 

The SMALL SCIATIC NERVE accompanies the sciatic vessels 
through the lower part of the great sacrosciatic foramen, and, in 
this situation, lies below the pyriformis muscle. Its distribution 
is given in the preceding table. 

The GREAT SCIATIC NERVE arises by five heads, viz., the lum- 
bosacral cord and the upper four sacral nerves, and is, in reality, 
a direct continuation of the sacral plexus. It is the largest nerve 
of the body, and escapes from the cavity of the pelvis, through the 
great sacro-sciatic foramen, where it lies on the outer side of the 
pudic vessels and nerve. It sends an articular branch to the hip- 
joint, supplies four muscles to the back of the thigh, and, by its 
terminal branches, supplies all the muscles of the leg and foot. 

The great sciatic nerve can be most easily felt at the fold oi 
the nates, by pressing between the great trochanter of the femur 
and the tuberosity of the ischium. The sitting posture of the 
body, therefore, if directed long towards one side, is liable to pro- 
duce numbness of the parts supplied by this nerve, on account 
of the pressure created upon the main nerve trunk. 

The PUDIC NERVE arises from the lower part of the sacral 
plexus and accompanies the pudic artery through both the 
greater sacrosciatic foramen and the lesser sacrosciatic foramen. 
Through the former it escapes from the cavity of the pelvis, and, 
through the latter, it again enters the cavity of the pelvis, having, 
between these two foramina, wound around the spine of the ischium. 
This peculiar course of the pudic artery and nerve has been ex- 



NERVES OF LEG AND FOOT. 



493 



plained by some, as an effort on the part of nature to prevent 
pressure upon these parts, at the spine of the ischium, during 
labor, since this portion of bone greatly assists in producing rota- 
tion of the head of the child. 



NERVES OF THE LEG AND FOOT. 



EXTERNAL 
POPLITEAL 

NERVE. 
(Peroneal.) 



/ v A , . , , , ( Three in number. 

(i) Articular branches, -j Distributed to knee -joint. 



{Two or three in number. 
Supply integument of outer and back part 
of the leg. 



'Muscular (to muscles in front part of leg 
and to the peroneus tertius.) 



(3) Anterior Tibial 

Nerve. 



External 
branch. 



Extensor brevis digitorum. 
Articulations of the tarsus. 



C Integument 
branch. ) 



of the adjoining 



J sides of the great and 2nd 



toes. 



(4) Musculo-Cutane-^ 
ous Nerve. 



Muscular.\l ermensl ™&} 5 ' 
I Peroneus brevis. 



External 
branch. 



r Integtwienl of outer side of 
foot and ankle. 
Integument of the adjoining 
sides of 3rd, 4th and 5th 
toes. 



C Integument of the inner side of 
Internal J the foot and ankle 

branch ^ Intc S umcnt of the adjoining 

sides of 2nd and 3rd toes 

^ and inner side of great toe. 



494 



NEUROLOGY. 



NERVES OF THE LEG AND FOOT— Continued. 



INTERNAL 

POPLITEAL 

NERVE. 



(i) Articular. 



(2) Muscular . 



j Three in number. 
' ' * l ( Distributed to knee-joint. 

f Gastrocnemius. 
J Plantaris. 
• • • • *j Soleus. 
I^Popliteus. 

f Formed by two filaments, one from each of 

, . _ „ the popliteal nerves. 

(3) External Saphe- J r r 

nous Nerve. , Integmnmt f t h e outer side of foot and the 
[ little toe. 



f Muscular . . 



Flexor longus pollicis. 
Flexor longus digitorum. 
Tibialis posticus. 



Plantar j Integument of heel and inner 
cutaneous. \ part of sole of foot. 



(4) Posterior Tibial. 
Nerve. 



Internal 
Plantar. 



f Integument of 
Digital 
branches. 1 inner 
[ foot. 



J the 3^ toes on 
I inner side of 



External 
Plantar. 



f Flexor brevis 
[ digitorum. 
[ Abductor polli- 

Muscular..-! F ^ r brCTis 

pollicis. 
2 inner lumbri- 
cales muscles. 

Articular (to tarsus). 
_ Cutaneous (to sole of foot). 

f Flexor accesso- 

' Muscular.. J A /l US \ • . 

'■ Abductor mini- 

|_ mi digiti. 

f 1^ outer toes, 

a j. -c • 7 Flexor brevis 
Superficial \ { minimi digiti< 
Drancn. ^ interosseous 
[_ muscle. 



Deep 

branch. 



3rd and4thlum- 

bricales. 
Rest of interos- 

sei. 
Adductor polli- 

licis. [dis. 
Trans versus pe- 



NERVES OF LEG AND FOOT. 495 



SUMMARY OF THE NERVES OF THE LEG AND 

FOOT. 

The nerves of the leg and foot are indirectly derived from the 
great sciatic nerve ; since its two terminal branches supply these 
regions, by the aid of numerous branches of their own, to which 
special names have been applied. 

• The EXTERAL POPLITEAL or PERONEAL NERVE is the smaller 
of the two terminal branches of the great sciatic nerve, but, since 
it passes along the outer side of the popliteal space, it bears no 
special relation to the popliteal artery. It divides into the 
anterior tibial and the musculo-cutaneous nerves, about one inch 
below the head of the fibula. From its close relation with the 
biceps muscle it is liable to be divided in tenotomy of that muscle. 

The anterior tibial nerve bears a relation to the anterior 
tibial artery, and also to the dorsalis pedis artery, by means of 
its internal branch. Its points of distribution are given in detail, 
in the preceding tables. 

The musculo-cutaneous nerve runs between the peronei muscles 
and the extensor longus digitorum, and divides, after piercing the 
deep fascia, into its terminal branches, at about the lower third 
of the anterior aspect of the leg. 

The INTERNAL POPLITEAL NERVE is the largest of the two 
terminal branches of the great sciatic nerve. In the popliteal 
space, it lies in intimate relation with the popliteal artery and 
vein. At the lower border of the popliteus muscle, after giving 
off articular and muscular branches, and a branch to assist in 
forming the external saphenous nerve, it becomes the posterior 
tibial nerve. 

The posterior tibial nerve is at first internal and posterior to 
the posterior tibial vessel, but soon passes to the outer side. It 
divides into the two plantar nerves in an interval between the 
inner malleolus and the heel. 

The internal plantar nerve supplies the integument of three 
and a half toes on the inner side of the foot, in addition to some 
muscles. 

The external plantar nerve supplies the integument of one 
and a half toes on the outer side of the foot in addition to some 
muscles. 



49 6 neurology. 

The nervous supply of the toes is as follows : 

External saphenous nerve. . \ Outer side of dorsum of the foot and of the little toe. 

Musculo-cutaneous nerve . . \ Inner 4^ toes on the dorsum of the foot. 

^., . 7 { Adjoining sides of 1st and 2nd toes on the dorsum of the 

Anterior tibial nerve -j f J oot & 

Internal plantar nerve \ Inner 3^ toes on the sole of the foot. 

External plantar nerve \ Outer \\ toes on the sole of the foot, 



S YMPA THE TIC NER VES. 



497 



THE SYMPATHETIC NERVES. 

The sympathetic nerves are called the nerves of organic life, 
in contra-distinction to the cerebro-spinal nerves, which are 
called the nerves of animal life. The term " sympathetic " was 
originally applied to them from the belief that, by means of 
these nerves, distant organs were made to undergo similar 
changes through sympathy. This system of nerves controls, 
to a great extent, nutrition and growth, since its filaments 
are principally distributed to the muscular coat of the blood- 
vessels ; and, by effecting the contraction or relaxation of these 
muscular fibres, they are enabled to increase or diminish the 
calibre of the blood-vessels and thus proportionately to increase 
or diminish the amount of blood distributed to the various por- 
tions of the body. 

The sympathetic nerves are distributed, like those of the 
cerebro-spinal system, to all portions of the human body, and 
are thus enabled to affect the various tissues which enter into the 
formation of the human framework. The main nerve and its 
branches are most extensively distributed, either in connection 
with, or in relation to, the larger trunks of the cerebro-spinal sys- 
tem, and its points of special interest are found in the cranium, the 
cervical region and in the thoracic, abdominal and pelvic cavities. 
The sympathetic system of nerves may be stated, in general, 
to consist of the following parts: 

i. Ganglia. 3. Branches of distribution. 

2. Cords of communication. 4. Plexuses. 

The GANGLIA of the sympathetic system, are chiefly in rela- 
tion either with the main divisions of the cerebro-spinal axis, 
the vertebral column, the various sensory nerve trunks, or the 
various viscera. They may be divided therefore into those of 
the cranium, the prevertebral set, the ganglia of the spinal nerves, 
and the ganglia of the viscera. 

Within the cranium, and in its immediate region, there are 
found the following ganglia : 

Ganglion of Ribes. 

Gasserian ganglion. 

Meckel's ganglion. 

Ciliary ganglion. 

Otic ganglion. 

Submaxillary 



498 NEUROLOGY. 

Of these ganglia, five, are connected with the great sensory 
nerve of the face, namely, the $th cranial nerve ; while the remain- 
ing one, namely, the ganglion of Ribes, is situated upon the anter- 
ior communicating artery and serves to connect the sympathetic 
nerves of the two sides of the body. 

With each of the thirty-one pairs of nerves, which arise from 
the spinal cord, there is found to exist a ganglion upon the pos- 
terior or sensory root of the nerve. These ganglia may properly 
be classed with the Gasserian ganglion and the ganglia on the 
roots of the glosso-pharyngeal and pneumogastric nerves; since 
they indicate, simply, the intimate communication which exists 
between the sensory nerves of the cerebro-spinal system and the 
sympathetic nerves, in contra-distinction to the absence of such 
affinity in the motor nerves of the cerebro-spinal axis. 

In the cervical region, three ganglia of the sympathetic system 
exist which are called as follows : 

Superior cervical ganglion. 
Middle cervical ganglion, {thyroid ganglion). 
Inferior cervical ganglion. 
The first of these is the largest and is situated opposite to the 
2d and 3d cervical vertebrae ; the second is the smallest of the 
three, and is situated upon the inferior thyroid artery, at a point 
opposite to the 5th cervical vertebra ; while the third is situated 
between the neck of the 1st rib and the transverse process of the 
last cervical vertebra, and is in relation with the superior inter- 
costal artery. 

The prevertebral set of ganglia are situated in the vicinity of 
the head of the ribs and are smaller than the cervical ganglia 
just mentioned, which, however, properly belong to this set. 
This group includes the three cervical ganglia just mentioned, 
eleven or twelve dorsal ganglia, four or five lumbar ganglia, five 
sacral ganglia, and one, which is located upon the coccyx, and 
which is called the ganglion impar. 

The ganglia connected with the viscera are numerous and are 
placed principally in the thoracic and the abdominal cavities. 

The PLEXUSES of the sympathetic system of nerves are very 
numerous. The more important ones are as follows : 
Carotid plexus. 
Cavernous plexus. 
Meningeal plexus. 
Facial plexus. 
Cardiac plexuses. 
Coronary plexuses. 



PLEXUSES OF THE SYMPATHETIC. 



499 



Solar or epigastric plexus. 

Phrenic plexus. 

Cceliac plexus. 

Gastric plexus. 

Hepatic plexus. 

Superior mesenteric plexus. 

Suprarenal plexus. 

Renal plexus. 

Spermatic plexus. 

Aortic plexus. 

Hypogastric plexus. 

Pelvic plexuses. 
Most of these plexuses, as their names would indicate, are de- 
veloped upon some vessel and are continued upon its branches ; 
some of the plexuses, above mentioned, are formed to a greater 
or less extent by nerves derived from larger and more important 
plexuses ; while others possess, from the parts to which they are 
distributed, special importance. 

The carotid and cavernous plexuses are developed upon the 
internal carotid artery ; the former just before, and the latter after 
its entrance into the cavernous sinus. 

The cardiac plexuses are termed the superficial and the deep ; 
and the two coronary plexuses are secondary to them, since they 
derive from them their principal filaments, although the pulmon- 
ary plexuses also assist to form them. The superficial cardiac 
plexus is situated beneath the arch of the aorta and in front of 
the right pulmonary artery, while the deep, or great cardiac 
plexus is situated between the trachea and the arch of the aorta. 
The anterior coronary plexus accompanies the left coronary 
artery, while the posterior coronary plexus accompanies the right 
coronary artery. They are both formed by branches from the 
cardiac and pulmonary plexuses. 

The solar or epigastric plexus lies behind the stomach and 
surrounds the ccelic axis and the root of the superior mesenteric 
artery. It consists of a network of nerves and ganglia, the two 
largest of which ganglia lie in front of the crura of the diaphragm, 
and, from their shape are called the semi-lunar ganglia. The 
solar plexus is mainly formed by the splanchnic nerves and the 
right pneumogastric nerves, although the left pneumogastric and 
both of the phrenic nerves have been traced to it. By means 
of this plexus, the phrenic, the cceliac, the superior mesenteric, the 
suprarenal, the renal, the spermatic, and the ovarian plexuses arc, 
to a greater or less extent, formed. 



5oo 



NEUROLOGY. 



The aortic plexus, which is also formed largely by the solar 
plexus, but partly also from other sources, is situated in front of 
the aorta, between the superior and inferior mesenteric arteries. 

The hypogastric plexus covers and lies between the two com- 
mon iliac arteries, and is in close relation with the promontory of 
the sacrum. 

The pelvic plexuses are two in number and are situated on 
either side of the rectum. They are formed by the hypogastric 
plexus, the sacral ganglia, and thejirst four sacral nerves. They 
assist in forming numerous small plexuses, which accompany 
the various branches of the internal iliac artery, and to which 
names have been applied, corresponding to the artery upon 
which the filament are distributed. 

The CORDS OF COMMUNICATION which exist between the 
various parts of the sympathetic system of nerves, may be divided 
into the following sets. 

1. Those connecting the ganglia of the cranium, as well as the 

prevertebral ganglia, to the cranial nerves. 

2. Those connecting the prevertebral ganglia with each other, 

thus forming the two grand cords of the sympa- 
thetic system, upon either side of the vertebral 
column. 

3. Those connecting the various prevertebral ganglia to the 

spinal nerves, which are usually two for each ganglion. 

4. Those connecting the prevertebral ganglia to the visceral 

ganglia. 

5. Those connecting the various ganglia of the viscera with 

each other. 

The BRANCHES OF distribution of the sympathetic nerves 
pass, as a rule, through some of the above mentioned plexuses, 
and are then scattered among the various organs contained 
within the thoracic and the abdominal cavities, or are distributed 
to the various arteries of the trunk, the head and neck, the upper 
extremity, or the lower extremity. 

Among the more important nerves, which belong to the sym- 
pathetic system, may be mentioned the following. 

1. The superior cardiac nerves. 

2. The middle cardiac nerves. 

3. The inferior cardiac nerves. 

4. The great splanchnic nerve. 

5. The lesser splanchnic nerve. 

6. The small splanchnic nerve. 



THE S YMPA THE TIC NER VES. 



501 



The stiperior cardiac nerves of either side, descend from the 
superior cervical ganglion to the cardiac plexuses. 

The middle cardiac nerves, the largest of the three, connect 
the middle cervical ganglion of either side with the deep cardiac 
plexus. 

The inferior cardiac nerves connect the inferior cervical gang- 
lia with the deep cardiac plexus. 

The great splanchnic nerve is formed by branches from several 
of the thoracic ganglia, and descends, through the posterior me- 
diastinum, till it perforates the crus of the diaphragm, after which 
it terminates in the semilunar ganglion. 

The lesser splanchnic nerve arises from the tenth and eleventh 
thoracic ganglia, pierces the diaphragm with the preceding nerve, 
and terminates in the cceliac plexus. 

The small splanchnic nerve arises from the twelfth thoracic 
ganglion, and, after piercing the diaphragm, terminates in the 
renal plexus, and in the lower part of the cceliac plexus. 



SPLANCHNOLOGY. 



THE HEART. 

The heart is the hollow muscular organ which propels the 
blood in the arteries, during life. It is situated within the 
thoracic cavity, between the lungs, with its base nearly parallel 
with the median line, and its apex corresponding to the 5th inter- 
costal space and situated one inch to the left of a perpendicular line 
drawn through the left nipple. It is five inches in length, three 
and one-half inches in breadth, and two and one-half inches in thick- 
ness. In the male, it weighs from ten to twelve ounces, and in 
the female from eight to ten ounces. 

It has four distinct cavities, which are named the right and 
left ventricle, and the right and left auricle. Of these, the ven- 
tricles are the more capacious and their walls are of greater thick- 
ness. They are lined by a serous membrane, called the endocar- 
dium, which is continuous with the lining coat of the blood- 
vessels. 

The heart is attached at its base, by means of the aorta, to the 
posterior wall of the thorax, while its apex is free and capable of 
a limited amount of motion. 

The whole organ is enveloped in a fibrous sac, called the per- 
icardium, which is attached, at the base of the heart, to the great 
vessels, and which is lined internally by a serous membrane. It 
contains normally about one dram of fluid, for the purpose of lu- 
brication. It is continuous, below, with the central tendon of 
the diaphragm, and is separated from the chest wall, except at a 
limited area, by lung tissue. 

The relative weight of the heart to that of the body varies 
greatly in the foetus and in the adult, and it shows also a variation 
in the two sexes, but by no means in so marked a degree. 
Thus, in the foetus, the heart represents one-fiftieth of the 
entire weight of the body; while, in the adult male, it represents 
only one one-hundred and sixty-ninth, and, in the adult female 
one one-hundred and forty-ninth of the total weight. 

The area upon the anterior surface of the chest which corres- 
ponds to the situation of that portion of the heart, where it is in 
close relation to the chest wall and is uncovered by lung tissue, 
can be approximately defined by describing a circle, whose di- 



506 



ORGAN OF C/RCULA TION. 



ameter shall be two inches, taking as its centre a point midway be- 
tween the left nipple and the end of the sternum. 

The external surface of the heart is traversed by tivo grooves 
which mark the division into its four separate cavities. These 
grooves are called the interventricular and the auriculo-ventric- 
ular grooves. The first lies between the two ventricles on the 
anterior and posterior surface of the heart, and runs longitudin- 
ally, or in the long axis of that organ ; while the second marks 
the junction of the auricles and ventricles, and runs transversely 
across the heart. 

Cavities of the Heart. 

The RIGHT AURICLE receives the venous blood from the two 
venae cavse and empties it into the right ventricle. The right 
auricle presents a principal cavity or sinus and a small appendix, 
resembling in shape the ear of a dog, and called for that reason 
the auricular appendix. 

It has two large openings in its interior, for the vena cava as- 
cendens and the vena cava descendens ; and a smaller opening? 
called the coronary sinus, for the coronary vein which returns the 
blood from the substance of the heart itself. It presents also an- 
other large opening, called the auriculo-venticular opening, through 
which the blood flows into the ventricle and which is closed during 
the contraction of the ventricle by the tricuspid valve. This 
opening in health should have a capacity sufficiently large to 
admit three fingers of an adult. 

The cavity of the right auricle presents also small minute ori- 
fices called the u foramina Thebesii" at which points venous blood 
from the small veins of the heart is returned. These openings 
are sometimes closed by reduplications of the endocardium, al- 
though their orifices are so minute as to be probably occluded by 
muscular pressure when the auricle is in a state of contraction. 

The walls of this cavity are thinner than in any portion of the 
heart, measuring only a line in thickness. They are composed of 
two layers of muscular fibres, arranged as an external and an 
internal set. The outer layer is common to both of the auri- 
cles, while the internal layer is distributed to each auricle sepa- 
rately. The internal muscular layer consists of looped and cir- 
cular bands of muscle. The former arise from fibrous rings, 
situated between the auricle and the ventricle, while the circular 
fibres encircle the auricular appendix, and the openings of the 
veins, into which they extend for a short distance. It is through 
these circular fibres, that the venous openings are diminished in 



CAVITIES OF THE HEART. 



507 



size during the contraction of the auricle, and thus regurgitation 
of blood into the venae cavae is partially obstructed, although the 
absence of valves at their auricular openings prevents their total 
closure during the systolic action of the heart. The coronary 
veins, however, are provided with one or two valvular folds, the 
coronary valves, which exclude the possibility of regurgitation of 
venous blood into the muscular substance of the heart. 

During fcetal life, the right auricle allows of the passage of 
blood from the vena cava ascendens, through the muscular sep- 
tum, into the adjoining auricle. The opening for this purpose is 
called the "foramen ovale" and the blood from the descending 
vena cava is prevented from entering it by a septum called the 
Eustachian valve, which deflects the upper current of blood into 
the right ventricle, while it causes the inferior current to pass 
through the foramen ovale. After birth, however, this valve de- 
creases greatly in size, and the communication between the auri- 
cles becomes destroyed by the closure of the opening ; so that, in 
adult life, a simple depression in the auricular septum termed the 
'' fossa ovalis" and a circumscribing ring called the annulus ovalis 
or isthmus of Vieusseus, mark the seat of its former existence. 

The aperture between the auricles fails, however, to become 
entirely closed in about fifty per cent of all the hearts opened for 
inspection, a small aperture being usually discovered on the up- 
per margin of the fossa ovalis ; but it is too small in extent to 
have any important effect upon the muscular power of the 
auricle. 

Two other points only within this cavity require mention, 
one of which is a small tubercle, supposed by Lower to assist in 
directing the current of blood through the tricuspid orifice, and 
called, from the discoverer, the " tubercle of Lower ; " and certain 
small prominent muscular columns, in the auricular appendix, to 
which the name " musculi pectinati" has been applied, from their 
supposed resemblance to the teeth of a comb. 

The cavity of the right auricle has been ascertained to be 
capable of containing about two ounces of fluid when moderately 
distended. 

The LEFT AURICLE of the heart is slightly smaller than the 
right auricle, and has thicker walls ; measuring from one-half to 
two lines in thickness. It receives blood from the lungs by the 
four pulmonary veins, which empty into its cavity by four distinct 
openings. These openings have no valves. The left auricle, like 
that of the right side, opens into the corresponding ventricle, by 
an auriculo-ventricular orifice which is closed by the mitral valve. 



508 



ORGAN OF CIRCULA TION. 



The arrangement of the muscular fibres of this auricle differs in 
no respect from that of the right side. 

The VENTRICLES, in all warm blooded animals, constitute the 
bulk of the heart. They are characterized by the great thickness 
of their walls, and have a fluid capacity in excess of that of the 
auricles. The right ventricle, by the experiments of Robin, is 
said to contain about one-eighth more than that of the left side. 
It is by the powerful action of the ventricles, that blood is pro- 
pelled through the systemic and pulmonary vessels. 

The cavities of both ventricles are conoidal in form and pre- 
sent a triangular-shaped section. The cavity of the right ven- 
tricle is broader and shorter than that of the left ventricle. 

The inner surface of both of the ventricles present for in- 
spection prominent muscular ridges and papillae, called columnce 
carnece. These are of three distinct varieties; the first variety 
being attached to the wall of the heart by their entire length, the 
second by the two extremities only, and the third by one extremity 
only. From these columnar carneae, fibrous cords, called chordce 
tendinece arise and pass to the free border of the mitral and tri- 
cuspid valves, which close the two auriculo-ventricular openings. 
These fleshy columns, the columnar carnese, interlace in every 
direction, giving the internal surface of the ventricles a reticulated 
appearance. This arrangement evidently assists in the complete 
expulsion of the contents of the ventricle during its contraction. 

The walls of the left ventricle are thicker than those of the 
right ventricle. Bouillard gives from his researches, the thickness 
of the left ventricle as seven lines, and that of the right ventricle 
as two lines and a half. 

The muscular fibres of the ventricles are arranged in two lay- 
ers, a superficial and a deep set. The superficial layer is common 
to both ventricles. The fibres composing it arise from fibrous 
rings at the auriculo-ventricular orifices, and pass in a spiral di- 
rection from right to left, from the base to the apex of the 
heart. At this point they dip into the substance of the heart, 
and, passing to its interior, become lost in the columnse carneae, 
which are chiefly formed by these fibres. The deep set of fibres 
are circular, and invest each ventricle separately. 

The muscular fibres of the heart differ, in four ways, from those 
of voluntary muscles in their microscopical appearance and ar- 
rangement. They are, in the first place, smaller in their size than 
ordinary muscular fibres and are granular in their structure ; 
again they join with each other, while ordinary muscular fibres 
run as separate structures from their point of origin to their 



VALVES OF THE HEART. 



509 



point of insertion, being enveloped in an investing sheath. In 
the third place they are, as a rule, beyond the control of the will y 
although they possess the striated appearance of voluntary mus- 
cle ; and finally they are destitute of sarcolemma. 

In each of the ventricles, two orifices are perceived ; of 
these, the auriculo-ventricular openings, have been already con- 
sidered in the description of each of the auricles, the other two 
are termed respectively the aortic and pulmonary openings, and 
serve to allow of the escape of the blood, during the contraction 
of the ventricles, into the arteries bearing the same name as 
these openings. 

That portion of the right ventricle, which approaches the ori- 
fice of the pulmonary artery, is conical in shape and is called the 
conus arteriosus, or infundibulum. 

That part of the left ventricle adjoining the root of the aorta 
is sometimes called the aortic vestibule of Sibson. Its walls are 
fibrous in character, and it remains uncollapsed during systole and 
disastole. 

Valves of the Heart. 

The valves of the heart are four in number, and close the two 
auriculo-ventricular, the aortic, and pulmonary openings. 

The mitral valve and the tricuspid valves perform the first 
office, in the left and right heart respectively ; while to the aortic 
and pulmonary valves the name " semilunar " is applied, from the 
shape of each of the three flaps, of which they are composed. 

The mitral VALVE, which closes the left auriculo-ventri- 
cular opening, consists of two segments or flaps, which, when 
closed together, prevent the regurgitation of blood from the left 
ventricle into the left auricle. Its flaps have no inherent rigidity, 
as exists in the semilunar valves, but are prevented from passing 
into the auricle by the chordae tendineas, which serves to attach 
them, either to the columnae carneae, or directly to the walls of the 
heart. These chordae tendineae are also present in the same rela- 
tion to the tricuspid valve in the right heart. The two flaps or 
segments forming the mitral valve are of unequal size, the largest 
segment lying in front and the smaller one posteriorly. 

The larger segment, when not closed, lies nearly over the aortic 
orifce,a.nd is supposed to prevent the blood from entering the 
aorta, during the distension of the left ventricle. 

The mitral valve is situated, in health, at a point correspond- 
ing with the 3d intercostal space, upon the external surface of the 
chest, and about one inch from the left border of the sternum. 



5io 



ORGAN OF CIRCULA TION. 



The two segments of the mitral valve arise from the fibrous 
rings situated at the auriculo-ventricular opening, and consist of 
a reduplication of the endocardium, or lining membrane of the 
heart, strengthened by a layer of fibrous tissue and a few muscu- 
lar fibres. The chordae tendineae are attached to the segments 
of the mitral valve in three situations. 1st, at the edge nearest 
the point of origin, 2d, at the centre of each segment, where 
the valve is specially thickened for that purpose, and 3d, at the 
marginal border of each segment. 

The same arrangement can also be found at the tricuspid 
valve, but the number of tendinous fibres attached to the mitral 
valve, is much smaller than those of the tricuspid valve, and 
their size and strength is greatly increased, to bear the excessive 
strain dependent on the powerful contraction of the left ven- 
tricle. 

The TRICUSPID VALVE is situated in the right ventricle and 
closes the right auriculo-ventricular opening. It consists of three 
segments or flaps which are triangular in shape, and to which the 
chordae tendineae of the right ventricle are attached. 

Like the mitral valve, its segments possess no inherent rigid- 
ity. They are, however, adherent to each other at that portion 
of their free margins, which is nearest the fibrous ring from 
which they arise, and they thus form a continuous membranous 
band at the immediate circumference of the auriculo-ventricular 
opening. 

The largest of the three segments is placed at that portion of 
the auriculo-ventricular orifice, which is nearest to the pulmonary 
artery, and doubtless serves to prevent the blood from entering 
that vessel during the auricular systole of the heart. 

The cJiordce tendinece attached to the segments of the tricus- 
pid valve are finer and more numerous than those attached to the 
mitral valve. 

The SEMILUNAR VALVES protect the aortic and the pulmonary 
orifices of the heart. By them the blood, thrown from the cavi- 
ties of the two ventricles, is prevented from again returning to 
the heart during its period of rest or diastole. 

They consist of three semi-circular folds so attached to the 
walls of the arteries as to present a concave surface, which looks 
towards the cavity of the vessel when the valves are closed. 

The free margin of each segment is thicker than in its central 
portion, being strengthened, in that part, by a bundle of tendinous 
fibres. It presents also a fibro-cartilaginous nodule, called the "cor- 
pus Arantii." From this nodule, tendinous bands radiate in every 



VALVES OF THE HEART. 



511 



direction towards the attached margin of the valve, except at two 
narrow lunated spots, called lunula, on each side of the nodule, 
where only the reduplicated endocardium exists, thus rendering the 
valve extremely thin at these points. During the passage of blood 
from the ventricles, during the systole of the heart, the segments 
of these valves disappear within recesses in the coats of the aorta 
and pulmonary artery, the sinuses of Valsalva, thus affording 
uninterrupted escape for the blood-current; but, during the 
diastole of the ventricle, when the current of blood in the large 
vessels is checked, and partly thrown back by their own elastic 
coats, these segments become immediately expanded and effec- 
tually close the orifice at the entrance to the tube. It is during 
the period of closure of the semilunar valves, that we are en- 
abled to perceive the function of the corpora Arantii and the thin 
lunated portion of each of the three segments. 

These segments when closely approximated, being circular in 
shape, would leave a central orifice were not the cartilaginous 
nodules so formed as to completely fill the empty space ; while 
the thinned condition of the valve assists in a more perfect adap- 
tation of these cartilaginous nodules, than would be ensured were 
the. valves rigid and unyielding. 

The segments of the semilunar valves differ from those of the 
mitral and tricuspid valves in the following respects. 

1st. They possess from their form and large supply of fibrous 
tissue, an inherent rigidity and tenacity of shape, not 
present in the auriculo-ventricular valves. 
2d. They open out of the ventricle and not into its cavity. 
3d. They possess no chorda tendinea, being able to resist pres- 
sure without assistance. 
The semilunar valves of the aortic and pulmonary orifices also 
differ from each other in the following points of interest. 

1st. The segments, composing the aortic valve, are thicker and 

stronger than those of the pulmonary valve. 
2d. The lunulas are more distinct in the aortic valve. 
3d. The corpora Arantii are larger and more prominent in the 

aortic valve. 
4th. The openings of the coronary arteries are in close relation 

with the aortic valves. 
5th. The sinuses of Valsalva, in the aorta, {sinuses aortic i) are 
deeper than those in the pulmonary artery, in order to 
accommodate the increased thickness of the segments 
of the aortic valve. 



512 ORGAN OF CIRCULA TION. 



Vessels and Nerves of the Heart. 

The heart substance derives its nutrition from blood conveyed 
to it by the coronary arteries, during the diastole of the heart ; 
the propelling power of the coronary circulation being the force 
of gravity and the elastic recoil of the aorta, although it is as- 
sisted by the relaxed condition of the walls of the heart. 

The veins of the heart comprise I. the great cardiac vein, 2. 
the smaller or anterior cardiac veins, and 3. the vencs cordis mini- 
ma (vena Thebesii). These veins accompany the arteries and 
return their blood into the cavity of the right auricle. 

The lymphatic vessels of the heart terminate in the right lym- 
phatic ducts and in the thoracic duct. 

The nerves distributed to the heart assist in forming the 
superficial and the deep cardiac plexuses, and also the posterior 
and the anterior coroyiary plexuses. These plexuses are formed 
by sympathetic nerve fibres, derived from various sources, and 
by filaments from certain cranial nerves. A description of these 
plexuses and their distribution will be given in the pages descrip- 
tive to the sympathetic system. 

Rings of the Heart. 

The heart has four fibrous rings within its substance, which 
are situated at the two arterial and the two auriculo-ventricular 
openings. These rings serve as points of attachment for the mus- 
cular fibres, for the valves of the heart, and for the coats of the blood- 
vessels. 



THE PERICARDIUM. 

The pericardium is a fibro-serous sac, which contains the heart 
and the commencement of the large vessels. It is conical in 
shape and is attached, at its base, to the central tendon of the 
diaphragm, and, at its apex, to the great vessels, upon which it is 
prolonged for a space of two inches. 

It is continuous above, with the deep layer of the cervical 
fascia ; it is in relation, posteriorly, with the roots of the lungs, the 
oesophagus, and the descending aorta ; it is invested, laterally, by 
the pleura, and is in close relation with the phrenic nerve; and 
in front, the thymus gland, the lungs, the pleurae, the sternum 
and the left costal cartilages are in close proximity to it. 



IRCULATION OF THE BLOOD. 

hillaries. \th. Veins. 

— Thfht, while its apex looks downwards, forwards, and to the left. 

— It use, and the Ventricles, especially the left, towards the apex of the cone. 

— Th " Septum ; " that portion which separates the Auricles being termed 
Septum Cordis" is employed in an absolute manner, the Septum of the 

— Bei the blood passes. 

— Z'/.ame of the " Pulmonic Heart," and contain venous blood ; while that 

ood. 
— Inlicular, blood passes out into a Ventricle. 
— Inive latter it leaves the Ventricle. 



-At 



— T 
— T 



/ from the Auricle, but prevents it from passing back ; the other, named 



■It 1: Auricle and Right Ventricle, called " Tricuspid," and another between 
llmonary Artery and the Aorta, and are known respectively as the " Pul- 



stole " and "Diastole" of the Heart, we invariably refer to the cone 



ic names are alternate. Thus, the two Auricles are in a state of con- 

:les are dilating, and vice-versa. 
— Q sound is heard, the Ventricles are contracting and the Auricles are 

j 
— Dthe second, the Auriculo- Ventricular valves are open, and the Arterial 

— "V\ is called Regurgitation ; when proceeding from a valve that should be 

— Wjwhose name begins with V, it enters one whose name begins with A, 
me beginning with V, as shown by the following diagram : 



ebesii. 




SYNOPSIS OF THE STRUCTURE OF THE HEART, AND THE CIRCULATION OF THE BLOOD. 

The Organs of Circulation are — ist. The Heart. 2d. Arteries. $d. Capillaries. 4th. Veins. 
-The Heart is a conical-shaped organ, situated in the thorax in such [a manner that its base looks upwards, backwards, and to the right, while its apex looks downwards, forwards, and to the left. 
-It is a hollow organ. In its interior are four cavities, viz. : two Auricles and two Ventricles. The Auricles are situated at the base, and the Ventricles, especially the left, towards the apex of the cone. 

These cavities are designated respectively the Right and Left Aulricle, and the Right and Left Ventricle. 
-The cavities of the right side have no direct communication with those on the left, being separated by a vertical partition called a " Septum ; " that portion which separates the Auricles being termed 

"Septum kuricularum," while that which separates the Ventriclles is called " Septum Ventriculorum." When the the term "Septum Cordis" is employed in an absolute manner, the Septum of the 

-Between the cavities of the same side there is a free communication by an opening, called the Auriculo-Ventricular, through whichj the blood passes. 

— The Cavities on the right side of the Septum, consisting of the Right Auricle and Right Ventricle, are frequently known by the name of the " Pulmonic Heart," and contain venous blood ; while that 
portion on the left, containing the Left Auricle and Left Ventricle, is styled the "Systemic Heart," and contains arterial bipod. 

—Into each Auricle there are five openings ; by four uf these, the m inths of veins, the blood enters, and by one, the Auriculo-Ventricular, blood passes out into a Ventricle. 

—Into each Ventricle there are two openings, viz.: the Auiiculo-Venjtricular and the Arterial. By the former the blood, enters, by the latter it leaves the Ventricle. 

—At each opening of a Ventricle is placed a valve, one of which, called the Auriculo-Ventricular, allows the blood to enter the cavity from the Auricle, but prevents it from passing back ; the other, named 
Arterial, allows the blood to leave the Ventricle, but prevents it from returning. 

—It thus appears that there are fourvalves employed in the transmission of the blood through the Heart, viz.: one between the Right Auricle and Right Ventricle, called "Tricuspid," and another between 
the Left Auricle and Left Ventricle, named " Mitral," and sometimes " Bicuspid." The two other valves are situated in the Pulmonary Artery and the Aorta, and are known respectively as the " Pul- 
monic " and " Aortic " valves. 

. — The contraction of the walls of the cavity is called its " Systole," and the relaxation its " Diastole." When we speak of the " Systole " and " Diastole " of the Heart, we invariably refer to the condi- 
tion of the Ventricles. 

. — The contraction and dilatation of cavities of the same generic name are synchronous and isochronous, while those of different generic names are alternate. Thus, the two Auricles are in a state of con- 
traction and dilatation at the same time, as is also the case with the Ventricles, but when the Auricles are contracting the Ventricles are dilating, and vice-versa. 

:.— On listening over the region of the Heart, two sounds are heard, known as the " First " and " Second " sounds. When the first sound is heard, the Ventricles are contracting and the Auricles are 
dilating, while during the second sound, the Auricles and the Ventricles are filling with blood. 

. — During the first sound of the Heart, the Auriculo-Ventricular valves are shut and the Arterial valves are are open ; while, during the second, the Auriculo-Ventricular valves are open, and the Arterial 
valves are closed. 

.—When an abnormal sound proceeds from a valve that should be shut, it shows that the blood i 
open, it then is said to be "Obstruction." 

. — With regard to the course of the blood through the Heart, it may be stated in general terms that, when the blood leaves an organ whose name begins with V, it enters one whose name begins with A, 
and vice-versa; while in the tissues, when it leaves an organ beginning with A. it enters one beginning with C, and passes into one beginning with V, as shown by the following diagram : 



iking a retrograde direction, and is called Regurgil 



rocceding from a valve that should be 



Cava Descending, Cava Ascending, Coronary Veins, and Foramina Thebesii, 



PULMON/ 




THE PERICARDIUM. 



513 



The internal or serous layer of the percardium forms a sheath 
for the aorta and the pulmonary artery for the first two inches of 
their extent ; and is then reflected upon the venae cavaa, the pul- 
monary veins, the external surface of the heart, and subsequently 
upon the inner surface of the fibrous layer. 

The fibrous layer of the pericardium is prolonged upwards upon 
the great vessels of the neck, and becomes continuous with the 
deep layer of the cervical fascia. 



5 14 ORGANS OF DIGESTION. 



\ THE ORGANS OF DIGESTION. 

Digestion of food is carried on within a group of connecting 
organs, termed the alimentary canal. Associated with it are cer- 
tain accessory organs, that also contribute greatly to the proper 
performance of digestion and assimilation. 

The alimentary canal, if considered as an individual structure, 
is a musculo-membranous tube, which is lined throughout with 
a mucous membrane, and which extends from the mouth, above, 
to the anus, below. Its length has been variously estimated from 
twenty-seven to thirty feet, and its different component parts have 
each received a special name. 

In the mouth, we find provision made for the mechanical di- 
vision of the food (mastication), and, through the glands of the 
mouth, for the admixture of a fluid, the saliva ; between this 
point and the stomach, are comprised the organs of deglutition, 
viz., the pharynx and oesophagus, which convey the food to the 
stomach ; in the cavity of the stomach, chemical changes occur, 
and the reduction and solution of some of the elements of food 
takes place ; in the small intestine, which is connected with the 
stomach, the admixture of bile and the pancreatic fluid occurs, 
by which complete digestion of food is accomplished, and most 
of its nutritive properties are here absorbed, through the blood- 
vessels and lacteals ; finally, in the large intestine, the waste mat- 
ter contained within the food is voided, and, to a certain extent, 
excretion of waste products is carried on. 

The following table shows the subdivisions of the alimentary 
canal and the accessory organs connected with it. 

Alimentary Canal. 

{ Duodenum, 
(i) Mouth. (5) Small intestine. •] Jejunum. 

(2) Pharynx. ( Ileum. 

(3) CEsophagus. (Caecum 

(4) Stomach. (6) Large intestine> 3 Colon. ' 

( Rectum. 



Accessory Organs. 

(1) Teeth. 

I Parotid. (3) Liver. 

(2) Salivary glands. . < Submaxillary. (4) Pancreas. 

( Sublingual. (5) Spleen. 



THE MOUTH. 



515 



The alimentary canal may be again divided into two parts, as 
follows. 

1. The part located above the diaphragm, which may be called 

the supra-diaphragmatic portion. 

2. The part situated below the diaphragm, which may be 

called the infra-diaphragmatic portion. 
Each of these portions may be subdivided into three parts, as 
is indicated below. 

! Mouth (oral, or buccal cavity). 
Pharynx. 
CEsophagus or gullet. 



Infra-diaphragmatic portion. . . 



f Stomach. 

! Duodenum. 
Jejunum. 
Ileum. 

i Caecum. 
Colon 
Rectum. 



The supra-diaphragmatic portion is ingestive in function, and 
has as appendages, the tonsils, the parotid, the submaxillary, and 
sublingual glands. 

The infra-diaphragmatic portion is digestive and egestive in 
function, and has as appendages, the liver, the spleen, and the 
pancreas. The first two organs contained in this portion, viz., the 
stomach and the small intestine, comprise the digestive apparatus, 
while the remaining portion, the large intestine, comprises the 
egestive apparatus. 

When the intestinal canal is spoken of, it designates that por- 
tion of the alimentary canal, which extends from the pyloric ori- 
fice of the stomach to the anus. 

THE MOUTH. 

The buccal cavity, which is the superior portion of the ali- 
mentary canal, contains, for special examination, the following 
parts : 

1. The tonsils. 

2. The tongue. 

3. The salivary glands. 

The bony structures which enter into the formation of the 
mouth, with the exception of the teeth, which will not be con 
sidered in this volume, have already been described in the chap- 
ter on osteology. 

The TONSILS arc small, slightly elongated bodies, which lie 
in the space between the anterior and posterior pillars of the soft 



5 1 6 ORGANS OF DIGESTION. 

palate, and which correspond, in their situation, to the angle of 
the jaw. They contain twelve or fifteen large spaces within their 
substance, from which smaller follicular depressions extend into 
the structure of the gland. These spaces and depressions are 
lined by a continuation of the mucous membrane and the epe- 
thelial layer of the throat. The tonsils are in close relation 
with the internal carotid and the ascending pharyngeal arteries. 

The TONGUE presents for examination a base, an apex, an 
upper surface or dorsum, and an under surface. 

The tongue is composed of a median fibrous septum, of a hyo- 
glossal membrane, of a mucous membrane, which is extremely 
thick upon its upper surface, of an extrinsic and an intrinsic set of 
muscles, and of vessels and nerves. 

The base of the tongue is attached to the hyoid bone, to the 
epiglottis, and, by means of muscles, to the soft palate and to 
the pharynx. 

The dorsum of the tongue contains three varieties of papillae, 
called the filiform papilla, the fungiform papillce, and the circum- 
vallate papillce, by which the special sense of taste is chiefly per- 
formed. The first set lie upon the sides of the tongue, the sec- 
ond set in the centre of the dorsum, while the third set are ar- 
ranged, in the form of a semi-circle^ at the base of the tongue. 
These papillae are named from their peculiar shape and forma- 
tion. 

The under surface of the tongue is connected with the hyoid 
bone and the lower jaw. Its mucous membrane is reflected. 
over the floor of the mouth, to the inner surface of the gums, 
and, in front, forms a prominent fold, called the frcenum linguce. 

The exti'insic muscles of the tongue comprise the stylo-glossus, 
the hyo-glossus, the genio-hyo-glossus, and the palato-glossus 
muscles. v 

The intrinsic muscles of the tongue comprise the transverse 
lingual fibres, the superior lingual fibres, the inferior lingual 
fibres, and the perpendicular fibres of the organ. 

The glands of the tongue comprise two sets, namely, a follicu- 
lar set, which are aggregated upon the posterior third of the dor- 
sum of the tongue, and a racemose set, which lie upon the dor- 
sum, the sides, and the under surface of the tongue. 

Glands of the Mouth. 

The salivary glands are three in number, and are called the 
parotid, the submaxillary, and the sublingual glands. 

The parotid gland lies below and in front of the external ear, 



THE MOUTH. 



517 



and is of large size. Within it, are contained large vessels and 
nerves, which are forced to pass through it, either to reach the 
skull or to escape from its cavity. Its duct is called Stend s duct. 
It opens opposite the second molar tooth of the upper jaw, by 
penetrating the substance of the cheek and running obliquely 
beneath its mucous membrane. 

The submaxillary gland is intermediate in size between the 
parotid and the sublingual glands. Its duct is called Wharton s 
duct. It is about two inches long, and opens at the summit of a 
small papilla on the side of the frcenum of the tongue. 

The submaxmillary gland lies in close relation with the facial 
artery, and the submaxillary ganglion. 

The sublingual gland is the smallest of the three glands of the 
mouth. It is of an elongated shape, and lies beneath the mucous 
membrane of the floor of the mouth, where it forms a prominence 
near the fraenum of the tongue. Its ducts are from eight to 
eighteen in number, and are called the ducts of Rivinus. They 
open into the mouth, near the fraenum linguae or into the duct 
of Wharton. 

One of the ducts of Rivinus is longer than the others and 
is often called the duct of Bartholine. 

Within the cavity of the mouth the following points may be 
felt and perceived, which have a practical bearing. 

1. The coronoid process of the lower jaw, whose anterior border 

is quite prominent. 

2. The hamular process of the sphenoid bone, which can be 

felt behind the last molar tooth of the upper jaw. 

3. The lower portion of the pterygoid fossa and the internal 

pterygoid plate of the sphenoid bone, in about the 
same situation as the hamular process. 

4. A space between the coronoid process and the tuberosity of 

the lower jaw, where deep temporal abscesses may 
require puncture. 

5. The posterior palatine artery, which escapes at the inner 

side of the last molar tooth, and about one-third of 
an inch in front of the hamular process of the sphen- 
noid. 

6. The pterygo-maxillary ligament^ which forms a prominent 

fold behind the last molar tooth, when the mouth is 
wide open. 

7. Ite gustatory nerve> whose situation close to the last molar 

tooth of the lower jaw can bo detected by the sense 
of extreme tenderness to pressure. This nerve is often 



5 1 8 ORGANS OF DIGESTION. 

divided, in this situation, to relieve pain in cancer of 
the tongue. 
8. A space behind the last molar tooth, of sufficient size to 
allow of introduction of a tube for the purpose of 
feeding a patient, suffering from spasmodic contraction 
of the muscles of the lower jaw. 

THE PHARYNX. 

The pharynx is a musculo-membranous sac, four inches and 
a half in length, which extends from the base of the skull to the 
lower border of the cricoid cartilage of the larynx, where it be- 
comes continuous with the oesophagus. 

It is bounded, above, by the petrous portion of the temporal 
bone and by the basilar process of the occipital bone ; behind, it 
is in relation with the recti capitis antici muscles, the longi colli 
muscles, and the first five cervical vertebrae ; below, it is continu- 
ous with the oesophagus ; in fro7it, it is incomplete, and is at- 
tached, from above downwards, to the internal pterygoid plate, 
the pterygo-maxillary ligament, the lower jaw, the base of the 
tongue, the cornua of the hyoid bone, the stylo-hyoid ligament, 
the thyroid cartilage, and the cricoid cartilage ; laterally, it is in 
relation with the styloid process of the temporal bone, the sty- 
loid and pterygoid muscles, the internal carotid artery, the inter- 
nal jugular vein, the glosso-pharyngeal, pneumogastric, spinal 
accessory, hypoglossal and sympathetic nerves ; and, in its lower 
portion, with the lateral lobes of the thyroid gland, the common 
carotid and lingual arteries, the sterno hyoid muscle, and the lin- 
gual nerve. 

Openings. 

The pharynx has seven openings, as follows : the two posterior 
nares, the openings of the two Eustachian tubes, the opening into 
the mouth, the superior aperture of the larynx, and the opening 
into the oesophagus. 

Coats. 

The pharynx has three coats, which, from without inwards, are 
called the muscular, the fibrous, and the mucous coats. The mid- 
dle coat is often called the pharyngeal aponeurosis. 

Muscles. 

The pharynx has five muscles, viz., the superior constrictor, the 
middle constrictor, the inferior constrictor, the stylo-pharyngeus 
and the palato-pharyngeus. The origin and insertion of these 






THE (ESOPHAGUS. 519 

muscles, as well as their source of nervous supply, can be found 
in the chapter on myology. 

Mucous Membrane. 

The mucous membrane is covered with squamous epithelium, 
below the level of the floor of the nares ; and, above that point, 
with columnar ciliated epithelium. It contains three varieties of 
glands, namely, simple follicular, compound follicular, and race- 
mose glands. The latter variety are most abundant in the upper 
part of the pharynx. 

Arteries. 

The arteries are four in number, viz., the ascending pharyn- 
geal, the pterygopalatine, the descending palatine, and branches 
of the superior thyroid artery. 

Nerves. 

The nerves are derived from the pharyngeal plexus. 



THE OESOPHAGUS. 

The oesophagus is a musculo-membranous tube, which com- 
mences in the median line of the neck, opposite to the $th cer- 
vical vertebra and the lower border of the cricoid cartilage of the 
larynx, and terminates, after passing through the diaphragm, at 
the cardiac opening of the stomach, on a level with the gt/i dorsal 
vertebra. It is nine inches long, and has relations, in the neck, 
with the trachea, the left lobe of the thyroid gland, the left re- 
current laryngeal nerve, the left common carotid artery; and, in 
the thorax, with the bifurcation of the trachea, the left bronchus, 
the arch of the aorta, the thoracic duct, the vena azygos major, 
the heart and pericardium, and the pneumogastric nerves. It 
passes through the oesophageal opening of the diaphragm, in com- 
pany with the pneumogastric nerves. 

Its muscular fibres consist of a longitudinal and a circular set. 

Its cellular coat forms a loose connection between its muscular 
and mucous coats, and contains its arteries, before they enter the 
mucous membrane. 

Its mucous membrane is pale in color, is very thick, is thrown 
into longitudinal folds, except when the bolus of food is passing 
through it, and contains small compound racemose glands, which 
are most abundant in its lower part. 

Its vessels are principally derived from the thoracic aorta, and 
its veins empty into the vena azygos major. 



520 ORGANS OF DIGESTION. 

Its nerves are derived from the pneumogastric and sympa- 
thetic. 



THE STOMACH. 

The stomach, or the chief organ of digestion, is situated in the 
left hypochondriac, the epigastric, and a part of the right hypo- 
chondriac regions. It consists, like the intestinal canal, of four 
coats, viz., the serous, the muscular, the cellular, and the mucous 
coats. It presents for examination two surfaces, an anterior and 
a posterior, two extremities, two curvatures or borders, and two 
openings. 

The anterior surf ace is in contact with the under surface of the 
liver, the diaphragm, and the anterior wall of the abdomen. 

The posterior surface is covered with peritoneum, and, by it, 
is separated from the great vessels of the abdomen, the solar 
plexus of nerves, the pancreas, and the diaphragm. 

The splenic end, or fundus of the stomach, is connected with 
the spleen by the gastro-splenic omentum. 

The pyloric end is in relation with the wall of the abdomen, 
the under surface of the liver, and the neck of the gall-bladder. 

The greater curvature gives attachment to the great omentum 
and lies above the transverse colon. 

The lesser curvature is connected to the diaphragm by the 
gastro-phrenic ligament, and, to the transverse fissure of the liver, 
by the lesser or gastro-hepatic omentum. 

The oesophageal or cardiac opening corresponds to the level of 
the 9th dorsal vertebra. 

The pyloric opening is situated at the pyloric extremity. 

Coats of the Stomach. 

The serous coat of the stomach covers its whole surface, except 
at the points of attachment of the gastro-splenic, the greater, and 
the lesser omenta. 

The muscular coat consists of three sets of fibres, called from 
their direction, the longitudinal, the circular, and the oblique 
fibres. The circular fibres form a sphincter muscle, at the pylo- 
ric orifice ; the longitudinal fibres are continuous with those of the 
oesophagus and the intestinal canal ; while the oblique fibres are 
a continuation of the circular fibres of the oesophagus. 

The cellular coat serves for the division of the blood-vessels, 
before they enter the mucous membrane of that organ. 

The mucous membrane of the stomach is thick at the pyloric 



THE INTESTINAL CANAL. 



521 



orifice and thin at the cardiac extremity. It has a honey-combed 
appearance, due to depressions upon its surface, called aveoli, 
into which depressions the glands of the stomach empty. It 
contains two kinds of glands, called peptic and mucous follicles, 
and a few scattered solitary glands, along its lesser curvature. 
The latter are considered by some as not true solitary glands, 
but as masses of lymphoid tissue. 

The peptic follicles are situated near the cardiac extremity, 
and consist of tubes which are lined, in their upper 
fourth, with columnar epithelium, and, in their deeper 
portion, with nucleated cells. 
The mucous glands are situated near the pyloric extremity, and 
are subdivided into from two to six tubular branches, 
which are lined, throughout their whole extent, with 
columnar epithelium. 

Vessels, Nerves, and Lymphatics. 

The vessels, lymphatics, and nerves of the stomach have been 
described in preceding chapters of this work. 

THE INTESTINAL CANAL. 

The intestinal canal extends from the pyloric orifice of the 
stomach to the anus. 

It comprises the three divisions of the small intestine, and the 
three divisions of the large intestine. It is partly ingestive and 
partly egestive in function, since the small intestine performs the 
greater part of absorption of the food, and aids also in the diges- 
tive processes ; while the large intestine does not participate in 
either. 

The intestinal canal comprises the following parts, which de- 
mand a special description. 

Duodenum. 

Small intestine -| Jejunum. 

Ileum. 

Ascending colon. 
Transverse colon. 
Descending colon. 
^ Rectum [Sigmoid flexure. 

The DUODENUM, so called from its correspondence, in 
length, to the breadth of twelve fingers, is ten inches long and is 
divided into three portions, called the ascending, the descending, 
and the transverse portions. Its shape is something like that of 
a horse-shoe, and its three portions measure respectively two and 
one-half inches, three and one-half inches, and four inches in 



Intestinal canal ■< 

Lar^e intestine 



Ccecum 
Colon 



522 ORGANS OF DIGESTION. 

length. It presents, on the inner wall of its descending portion, 
the openings of the pancreatic and bile ducts, which are usually 
contained within a small papilla upon its mucous surface. 

The JEJUNUM, the second portion of the small intestine, com- 
mences at the left of the 2d lumbar vertebra and is crossed by the 
superior mesenteric artery. It is larger and thicker than the ileum, 
and, as no line of division exists, its point of termination, and 
therefore its length, must remain a matter of measurement only. 

Its name is given to it from the fact that this portion of the 
intestine is usually found empty after death. Its length is usually 
given as two-fifths of the balance of the small intestine, after the 
length of the duodenum has been deducted. 

The coils of the jejunum lie in the immediate vicinity of the 
umbilicus, while those of the ileum lie below that level. 

The ILEUM comprises the remaining three-fifths of the balance 
of the small intestine, after the length of the duodenum has been 
deducted, and terminates at the ileo-ccecal valve, where it joins the 
first division of the large intestine. Its name is given from its 
twisted course. 

The CAECUM, the first division of the large intestine, is a cul- 
de-sac, about two and a half inches in length and the same in 
width, which is situated in the right iliac fossa of the abdomen, 
where it is retained in position by a fold of the peritoneum, called 
the meso-ccecum. It presents a tubular prolongation, called the 
appendix vermiformis, which varies from two to six inches in 
length, is of the diameter of a goose quill, is connected with the 
lower and back part of the caecum, and is usually directed up- 
wards and inwards behind it and is there retained by a fold of 
peritoneum. The ileo-ccecal valve, called also the ileo-colic valve, 
and the valve of Bauhin and of Tulpius, is formed by two cre- 
sceritic folds of the mucous and submucous coats of the intestine 
and by the circular fibres of the intestine. 

The COLON, or second portion of the large intestine, is usually 
subdivided, from the direction of its course, into four distinct por- 
tions, called respectively the ascending colon, the transverse colon, 
the descending colon and the sigmoid flexure. 

The ascending colon extends upwards to the under surface of 
the liver where it curves to the left, forming the hepatic flexure 
of the colon ; the transverse colon, called also the arch of the 
colon, continues from this point to the left hypochondriac region, 
where it bends downwards, forming the splenic flexure of the 
colon ; the descending colon extends from this point to the crest 
of the ilium, where it becomes the sigmoid flexure, and, finally, 



THE INTESTINAL CANAL. 



523 



this latter portion terminates in the rectum, at a point opposite 
the left sacro-iliac synchondrosis. 

The close relation of the colon to the gall bladder often causes 
a staining of that portion of the intestine after death. 

The ascending colon is bound down by the peritoneum to the 
quadratus lumborum muscle and the right kidney ; the transverse 
colon is extremely movable, since it is comprised between the two 
ascending layers of the great omentum ; the descending colon is 
also partially connected to the left kidney, the left crus of the 
diaphragm, and the quadratus lumborum muscle ; while the 
sigmoid flexure of the colon is again freely movable, being re- 
tained only by a loose fold of peritoneum. 

The RECTUM commences at the left sacro-iliac synchondrosis 
and terminates at the anus. It is about eight inches long and is 
divided into three portions called, respectively, the upper, the 
middle, and the lower portions. It is smooth and cylindrical in 
form, and, in this respect, differs from the other portions of the 
large intestine, which are saculated. 

The first portion extends to the third piece of the sacrum, and 
is about four inches long. It is almost completely surrounded by 
a fold of peritoneum, called the meso-rectum, and rests upon the 
sacral plexus of the left side. 

The middle portion extends from the third bone of the sacrum 
to the tip of the coccyx, and is about three inches long. It is 
in relation, in the male sex, with the triangular space at the base 
of the bladder, which corresponds to the trigone, and also with 
the vesiculae seminales and the under surface of the prostate gland. 
This relation is of surgical importance, if puncture of the bladder 
through the rectum be attempted. 

The lower portion of the rectum extends from the tip of the 
coccyx to the anus, and is about one inch in length. It is*invested 
by the two sphincter muscles of the rectum and by fibres of the 
levator ani muscle ; and is separated by a triangular space, called 
the perineum, from the bulb of the urethra, in the male, and from 
the vagina in the female. 

The LARGE and SMALL INTESTINE each consist of four coats, 
viz., the serous, the muscular, the cellular, and the mucous coats. 
The serous coat is formed by the peritoneum, the muscular coat 
consists of circular and longitudinal fibres, the cellular coat affords 
an opportunity for the division of vessels before they enter the 
mucous membrane, and the mucous coat forms the internal lining 
of the tubes. The small intestine contains the following points 
of interest. 



524 ORGANS OF DIGESTION. 

I. Valvules conniventes, which are crescentic reduplications of 
the mucous and submucous coats, extending into the 
intestine for about two-thirds of its circumference. 
They begin about two inches below the pyloric orifice 
of the stomach and are largest and most numerous im- 
mediately below the opening of the pancreatic duct 
and in the middle of the jejunum, while they nearly 
disappear in the lower part of the ileum. 

2. Villi) which are minute projections on the mucous membrane, 

about one thirty-fifth of an inch in height, and which 
are conical, cylindrical, or club-shaped. They are most 
numerous in the upper part of the small intestine. 

3. Glands or Crypts of Lieberkilhn, which are minute tubular 

depressions, found all over the small intestine and even 
in the large intestine and stomach. They are lined with 
columnar epithelium. 

4. Solitary glands, which are most abundant in the lower part 

of the small intestine, and which are usually situated 
upon the free margins of that tube, at a point most 
distant from its border of attachment. These glands 
are also arranged in groups along the course of the 
intestine, which are called Peyer s patches. The total 
number of these patches varies from twenty to thirty. 

5. Brunncr s glands < which are small conglomerate glands, and 

which exist chiefly in the duodenum and the com- 
mencement of the jejunum. 
The LARGE INTESTINE differs, in its construction, from the 
SMALL INTESTINE in the following respects. 

1. It is only about one-quarter of the length of the small in- 

testine. 

2. It is sacculated, while the small intestine is not. 

3. It is much larger in its diameter. 

4. It is much less movable, being attached, for the greater 

portion of its length, closely to the parietes of the 
abdomen, and the parts to which it bears relation. 

5. The valvules conniventes are indistinct, and, in some places, 

absent. 

6. The villi are either absent or are few in number. 

7. The glands of B runner are absent. 

8. The solitary glands and Peyer s patches are absent, except- 

ing at its upper portion. 

9. The tubular glands of Lieberkilhn are larger and more nu- 

merous than in the small intestine. . 



THE PERITONEUM. 52$ 

10. Its longitudinal muscular layer is arranged as three distinct 

bands, while, in the small intestine, it is evenly dis- 
tributed over its entire circumference. 

11. The serous covering of the large intestine does not com- 

pletely surround it, in all of its portions, and forms 
pouches, called appendices epiploicce. 

THE PERITONEUM. 

The peritoneum is the serous membrane which lines the ab- 
dominal cavity, and which invests the viscera. Its numerous 
prolongations and reflections may be arranged under three heads 
as follows : 

1. Omenta or epiploa. 

2. MESOS or MESENTERIES. 

3. Ligaments. 

The three following rules will assist the student as guides to 
the proper use and application of these terms. 

I. When a fold of the peritoneum connects the STOMACH to 
an adjoining organ, the fold is termed an omentum or epiploon. 

Of these there are three within the abdomen, viz. 

1. Gastro-hepatic or lesser omentum. 

2. Gastro-colic or greater omentum. 

3. Gastro-splenic omentum. 

II. When a process or fold of peritoneum connects any por- 
tion of the INTESTINAL CANAL (except the duodenum) to the 
abdominal wall, it is called a meso or mesentery, and a special 
name of any particular portion, process, or fold is obtained, by 
prefixing the word meso to the attached portion of the intestinal 
canal. As examples of this we have the following terms. 

Meso-caecum. 

Meso-colon. 

Meso-rectum. 

III. When the peritoneum connects either a solid or hollow 
organ which is not a part of the intestinal canal, to the adjacent 
parts, it is called a ligament. Thus we have formed certain liga- 
ments of the liver, the spleen, the uterus, the bladder, etc. 

The peritoneum may be divided into two layers termed the 
parietal and the visceral layer. The former covers the walls o( 
the abdominal cavity, and the latter is reflected upon the numer- 
ous viscera contained within it. 

The visceral layer of the peritoneum affords a partial covering 



526 ORGANS OF DIGESTION. 

only to some organs, a complete covering to others, while por- 
tions of organs are destitute of any peritoneal covering. 

Below will be found enumerated the conditions of the various 
viscera of the abdominal cavity, in respect to their peritoneal 
covering. 

Covered with Peritoneum. Partially covered with Peritoneum. 

Liver (almost entirely). Duodenum (descending and transverse por- 
Stomach (almost entirely). tions). 

Spleen. Colon, ascending and descending. 

Duodenum, ascending portion. Rectum, middle portion. 

Jejunum. Vagina (upper part of). 
Ileum. 

Transverse arch of colon. No covering of Peritoneum. 

Sigmoid flexure of colon. Rectum, lower part. 

Upper third of rectum. Bladder, lower part and neck. 

Ovaries. Bladder, anterior surface. 
Posterior portion of bladder. 
Uterus. 

The mesentery, which connects the small intestine with the 
abdominal parietes, has its root from the left side of the 2nd lum- 
bar vertebra to the right sacro-iliac synchondrosis. It extends 
therefore over a space of about six inches. The anterior border 
of the mesentery is from twenty to twenty-five feet in length, 
while its breadth is about four inches. It contains, besides the 
small intestine, the arteries, veins, glands, and lacteal vessels of 
the mesentery. 

The great or gastro-colic omentum consists of four layers, of 
which the most anterior and the most posterior layer belong to 
the greater cavity of the peritoneum, and the two internal layers 
belong to the lesser cavity. The two anterior layers descend 
from the greater curvature of the stomach and from the spleen, 
while the two posterior layers ascend to the transverse colon. 

The lesser or gastro-hepatic omentum extends from the trans- 
verse fissure of the liver to the lesser curvature of the stomach. 
Its free border, on the right side, contains the hepatic artery, the 
bile duct, and the portal vein, and forms the anterior boundary 
of the foramen of Winslow, which connects the greater and lesser 
cavities of the peritoneum. The relations of these parts in the 
transverse fissure of the liver, are as follows : duct, vein, artery, 
(D. V. A)., from right to left, the vein lying slightly behind the 
hepatic artery and the hepatic duct. 

The ligaments, which are formed by the peritoneum, comprise 
one of the stomach, four ligaments of the liver, five ligaments of 
the bladder, six ligaments of the uterus, and the suspensory lig- 
ament of the spleen. 



THE LIVER. 



THE LIVER. 



527 



The liver is the largest glandular organ in the body, and is 
mainly intended for the secretion of bile, although other func- 
tions of perhaps equal importance are performed by it. It is sit- 
uated in the right hypochondriac, the epigastric, and the left 
hypochondriac regions ; and it weighs from three to four pounds, 
when of normal size. It measures from ten to twelve inches 
in a transverse direction, from six to eight inches in the antero- 
posterior direction, and about three inches in the vertical direc- 
tion, in its thickest portion, which corresponds with the back por- 
tion of the right lobe. 

The liver presents for examination an upper surface, an under 
surface, an anterior border, a posterior border, a right extremity, 
and a left extremity. 

The upper surface is convex, and lies in relation with the dia- 
phragm. It is divided into two lobes of unequal size, called the 
right and left lobes of the liver, by a fold of peritoneum called 
the suspensory or broad ligament of the liver. 

The under surface is also divided by a fissure, called the longi- 
tudinal fissure, into two unequal portions, which form the right 
and left lobes. It presents also certain portions of the liver 
substance to which the names lobulus quadratus, lobulus Spi- 
gelii and lobulus caudatus are applied ; and also certain grooves, 
to which the names fissures are given, and which contain, respec- 
tively, the vena cava, the gall-bladder, and the ductus venosus, 
and a deep depression called the transverse fissure, or the gatezvay 
of the liver, where the portal vein and the hepatic artery enter, 
and the hepatic duct escapes. This surface is in relation with the 
stomach and duodenum, the hepatic flexure of the colon, and the 
right kidney and its supra-renal capsule. 

The right extremity is thick and rounded, and is in relation with 
the diaphragm and ribs. 

The left extremity is thin and flattened, and is in relation with 
the stomach and sometimes with the spleen. 

The anterior border corresponds, in male adults, with the free 
border of the ribs, but, in women and children, frequently extends 
below it. It affords attachment, by a deep notch, to a portion of 
the broad ligament of the liver. The free border of the liver can 
be most easily detected, by the uneducated hand, below the ensi- 
form cartilage, since it extends in this region, nearly halt" the dis- 
tance between the end of the sternum and the umbilicus. 



528 ORGANS OF DIGESTION. 

The posterior border is in relation with the aorta, the inferior 
vena cava, and the diaphragm ; to the latter of which it is attached. 

The liver is covered with peritoneum, with the exception of 
a small portion, situated at its posterior border, where the peri- 
toneum is absent. 

The liver has five lobes, five ligaments, five fissures, and five 
vessels, as follows. 

Ligaments. Vessels. 

Suspensory or broad. Hepatic artery. 

Right lateral. Portal vein. 

Left lateral. Hepatic veins. 

Coronary. Hepatic duct. 

Round. Lymphatic vessels. 

Lobes. Fissures. 

Right lobe. Longitudinal. 

Left lobe. Fissure for vena cava. 

Lobulus quadratus. Transverse. 

Lobulus Spigelii. Fissure for gall bladder. 

Lobulus caudatus. Fissure for ductus venosus. 

Ligaments. 

The longitudinal ligament (broad, falciform, or suspensory- 
ligament) receives its various names from its direction, its width, 
its shape, and its function. Its base, or broadest portion is at- 
tached to the posterior surface of the sheath of the rectus muscle 
of the right side, as low down as the umbilicus, and to the under 
surface of the diaphragm. It hepatic margin extends from the 
anterior border of the liver to its posterior border, and is con- 
tained in the groove, on the upper surface, between the right and 
the left lobe. This ligament consists of two layers of peritoneum ; 
and the anterior portion oi\\.<~> free edge contains, between its two 
layers, the round ligament of the liver. 

The two lateral ligaments are triangular in shape, and are com- 
posed of two layers of peritoneum. They serve to connect the 
extremities of the posterior border of the liver to the diaphragm. 

The coronary ligament also connects the posterior border of 
the liver to the diaphragm and is composed of two layers of peri- 
toneum ; but it differs from the lateral ligaments of the liver in that 
it is connected with the middle portion of the posterior border, 
while the lateral ligaments are attached at either extremity of 
that border. The coronary ligament is divided into two parts, 
by a deep notch or canal, in which is lodged the inferior vena cava, 
and at which point the hepatic veins of the liver commmunicate 
with that vessel. 



THE LIVER. 



529 



The round ligament is a fibrous cord which consists of the ob- 
literated umbilical vein of the foetus. It is contained in the 
free margin of the longitudinal ligament, until it reaches the 
anterior border of the liver, when it passes through the longitu- 
dinal fissure on the under surface of that organ, and is contin- 
ued, from that point, as the remains of the ductus venosus, in the 
fissure of that name, as far back as the inferior vena cava. 

Fissures. 

The five fissures of the liver are grooves upon its under sur- 
face, which separate the five lobes of the liver. 

The longitudinal fissure is a deep groove which extends 
from the anterior border to the centre of the organ, as the umbili- 
cal fissure, and, from that point, it is continued, as the fissure for 
the ductus venosus, to the posterior border of the liver. It joins 
the transverse fissure at a right angle ; this point of junction mark- 
ing the line of division between its two portions, viz., the umbili- 
cal fissure and the fissure for the ductus venosus. It is occa- 
sionally bridged over by a band of liver tissue, called the pons 
hepatis. 

The fissure for the ductus venosus is the posterior half of the 
longitudinal fissure of the liver, which lodges in the foetus, the 
ductus venosus, and, in the adult, a slender fibrous cord, which 
the obliterated remains of that vessel. 

The transverse or portal fissure is two inches in length, and is 
the deepest fissure of the liver. It extends transversely across 
the organ and joins the longitudinal fissure, at about its middle, 
at a right angle. It gives passage to the vessels of supply of the 
liver, and affords a point of exit for the hepatic duct. The rela- 
tions of the hepatic artery, the hepatic duct and the portal vein,, 
within this fissure, are from right to left, as follows : the hepatic 
duct lies to the right, the portal vein lies between the artery and 
the duct, but behind them both ; and the hepatic artery lies to 
the left. The connective tissue which holds these parts together 
is called the capsule of Glisson. It extends into the substance 
of the liver and invests the branches of each of these vessels. 

The fissure for the gall-bladder lies parallel with the longitudi- 
nal fissure of the liver, and extends from the anterior border of 
that organ to a point nearly corresponding to the right extremity 
of the transverse fissure. 

The fissure for the vena cava is occasionally a complete canal, 
and extends from the right extremity of the transverse fissure to 
the posterior border of the liver, where it joins the fissure of the 



530 



ORGANS OF DIGESTION. 



ductus venosus. In this fissure is perceived a deep fossa, at the 
bottom of which the hepatic veins of the liver escape to open into 
the inferior vena cava. 

Lobes. 

The five lobes of the liver present the following points of in- 
terest. 

The right lobe is very large, equalling or exceeding in size the 
combined volume of the four remaining lobes. It occupies the 
right hypochondriac region, and is separated from the left lobe 
by the suspensory ligament, upon its upper surface ; upon its 
lower surface, by the longitudinal fissure ; and, in front, by a deep 
notch upon its anterior border. Its under surface presents five 
points of interest, viz., the transverse fissure, the fissure for the 
gall-bladder, the fissure for the inferior vena cava, and two shal- 
low depressions, which lodge the hepatic flexure of the colon and 
the right kidney with its supra-renal capsule. 

The left lobe of the liver is situated in the epigastric and the 
left hypochondriac regions, and is smaller than the right lobe and 
flattened in its form. It occasionally extends to the spleen with 
which it then bears a relation, as well as with the stomach ; but 
with the latter it always lies in close relation. 

The lobulus qua drat us is so called from its square outline, and 
lies upon the under surface of the liver. Its boundaries are as 
follows ; 

In front, by the free margin of the lobe. 

Behind, by the transverse fissure. 

On the right, by the fissure for the gall bladder. 

On the left, by the umbilical fissure. 

The lobulus Spigelii lies at the back part of the under surface 
of the right lobe of the liver, and is bounded as follows. 

In front, by the transverse fissure. 

Behind, by the free margin of the lobe. 

On the right, by the fissure for the vena cava. 

On the left, by the fissure for the ductus venosus. 

The lobulus caudatus is so called from its resemblance to a tail 
to the right lobe. It connects the right lobe to the lobulus Spigelii, 
and separates the transverse fissure from the fissure for the vena 
cava. 

Vessels. 

The vessels of the liver are five in number, and present the 
following points of interest. 

The hepatic artery arises from the cceliac axis, and enters the 



. 



THE LIVER. 531 

transverse fissure of the liver. It is the vessel of nutrition of the 
organ. It probably terminates in the lobular plexus of veins in 
the centre of each of the lobules of the liver, but, according to 
some authorities its branches do not extend into the lobules. 

The portal vein is the main trunk of the portal system, and 
conveys blood from the intestinal tract, the stomach, and the 
spleen, to the transverse fissure of the liver. Its relations to the 
hepatic artery and duct, at this point, have been given in the de- 
scription of the transverse fissure. The portal vein gives off the 
following branches : 

1st. Right and left portal. 
2d. Vaginal branches. 
3d. Inter-lobular branches. 
4th. Lobular branches. 

The first two branches are distributed to the lobes of the same 
names. 

The vaginal branches are the main trunks of the portal sys- 
tem, after the vessels enter the substance of the liver. 

The inter-lobular branches are given off by the vaginal branches 
within the portal canals, and pass between tJie lobules of the liver. 
They give off converging branches, called lobular branches, which 
penetrate the substance of the lobules and assist to form the cen- 
tral vein of each lobule, to which the name intra-lobular vein is 
applied. 

The numerous lobular branches of each interlobular vein 
anastomose within the lobule and thus form what is called the 
lobular plexus of veins. 

The openings of the portal canals of the liver can be discerned 
from those of the hepatic veins, on section of the liver, since the 
latter stand wide open, being closely attached to the substance 
of that organ, while the portal veins are either entirely or par- 
tially closed, on account of the connective tissue which intervenes 
between them and the walls of the liver (capsule of Glisson). 

The hepatic veins are a direct continuation of the veins of the 
portal system, within the substance of each lobule of the liver. 
They arise from the lobular plexus of veins, and in reality, begin 
as the central or intra-lobular vein of each lobule. These intra- 
lobular veins escape at the base of each lobule as the sub- lobular 
veins, and these, by their union, assist to form the so-called hepa- 
tic veins. The hepatic veins open into the inferior vena cava, at 
a deep depression in the posterior border of the liver. 

The biliary ducts are the vessels which convey the bile from 
the liver, and which form, by their union, the hepatic duct. 



532 ORGANS OF DIGESTION. 

The method of origin of the biliary ducts is a matter of uncer- 
tainty. 

The lymphatic vessels consist of a superficial and a deep set. 
They principally accompany the blood-vessels. 

The nerves are derived from the solar plexus and from the left 
pneumogastric and the right phrenic nerves. 

The substance of the liver may be said to consist principally 
of liver cells, arranged in groups, to which the name lobules is ap- 
plied. These lobules are connected together by connective tissue, 
blood-vessels, ducts, and lymphatics. Each lobule is polygonal 
in shape, on transverse section, and leaf-shaped, on perpendicu- 
lar section, and measures about one-twentieth of an inch in diam- 
eter. It consists of the following component parts : 

1st. Liver cells. 

2d. A plexus of lobular veins. 

3d. The central or intra-lobular vein. 

4th. A plexus of lymphatic vessels. 

5th. A plexus of nerves. 

6th. A plexus of bile ducts (possibly). 
The external bile ducts comprise the following parts which de- 
serve special consideration. 

1st. The hepatic duct. 

2d. The cystic duct. 

3d. The ductus communis choledochus. 

4th. The gall bladder. 
The hepatic duct is formed by the junction of the two large 
excretory ducts of the right and left lobes of the liver. It is con- 
tained between the two layers of the gastro-hepatic omentum. 

The cystic duct, the duct of the gall-bladder, is about one 
inch in length. It assists to form the ductus communis chole- 
dochus. 

The ductus communis choledochus is formed by the junction 
of the cystic and the hepatic ducts, and is about three inches in 
length. It descends between the head of the pancreas and the 
descending portion of the duodenum, and, after perforating the 
muscular coat of the intestine, it opens into the cavity of the 
duodenum at the summit of a small papilla upon its inner 
wall, at a point about three inches from the pyloric orifice 
of the stomach, and usually in common with the duct of the 
pancreas. 

The gall-bladder is a pear-shaped sac, intended as a reservoir 
for the bile. It is three ox four inches in length, and is capable of 
containing from eight to twelve drachms. It lies in a fissure upon 



PANCREAS AND SPLEEN. 533 

the under surface of the liver, called the fissure for the gall-blad- 
der, and empties its contents through the cystic duct. 

The external bile ducts of the liver as well as the gall-bladder 
consist of a peritoneal coat, a ftbro-muscular coat, and a mucous 
coat. 

THE PANCREAS. 

The pancreas is a long flattened organ, of a reddish cream- 
color, situated opposite to the 2nd lumbar vertebra. It lies be- 
hind the stomach, and presents the following points of interest. 

A head or right extremity. 

A body or central portion. 

A tail or left extremity. 

A duct or the canal of Wirsung. 

The head is contained within the cavity of the duodenum, and 
is in close relation with the ductus communis choledochus and 
the pancreatico-duodenal arteries. 

The body is flattened, and extends transversely across the 
cavity of the abdomen. It has the following relations with sur_ 
rounding parts. 

In front. . . Stomach and Peritoneum. 

Left kidney and its capsule. 

Inferior vena cava. 
Aorta. 
. Vessels, (5) J The mesenteric arteries, j ^rior!' 
Portal vein. 
w Left renal vessels. 
Crura of the diaphragm. 
fc Left quadratus lumborum muscle. 

Above Coeliac axis, splenic artery and vein. 

Below Duodenum and superior mesenteric vessels. 

The tail lies in contact with the kidney of the left side and 
with the spleen. 

The duct, called the canal of Wirsung, communicates with 
the cavity of the pancreas, which extends throughout the en- 
tire length of the body of the gland. It joins with the ductus 
communis choledochus and opens, in common with it, at the 
summit of the small papilla on the inner aspect of the descend- 



534 



ORGANS OF DIGESTION. 



ing portion of the duodenum. In exceptional cases, however, it 
opens by a separate papilla of its own. 

The pancreas consists of a glandular structure, arranged as a 
racemose or conglomerate gland, and is similar in its appearance 
to the salivary glands. 

The arteries are derived from the splenic and the pancreatico- 
duodenal arteries. 

The veins open into the portal system, while its lymphatics 
open into the lumbar glands. 

The nerves are derived from the solar plexus. 



THE SPLEEN. 

The spleen is one of the accessory organs of digestion, and is 
situated in the left hypochondriac region of the abdomen, where 
it embraces the left extremity of the stomach. It is oval in its 
form, is of a dark reddish-blue color, and is connected to the 
stomach by the gastro-splenic omentum. It presents for exami- 
nation two surfaces, two extremities, and two borders. 

The outer surface is convex, and is in relation with the dia- 
phragm. It corresponds with the 9th, 10th and nth ribs. 

The inner surface is concave and, at its middle portion, it 
presents a vertical fissure, called the hilnm, where the vessels, 
nerves, and lymphatics enter. It is in relation with the stomach, 
the tail of the pancreas, and the diaphragm. 

The upper extremity is attached to the diaphragm by the sus- 
pensory ligament of the spleen. 

The lower extremity is in relation with the splenic flexure of 
the colon. 

The anterior border is thin, and presents a notch at about its 
centre. 

The posterior border is thick, and is in relation with the left 
kidney. 

The spleen is one of the ductless glands of the body, and is 
therefore classed with the thyroid and the thymus glands, and 
the supra-renal capsules. It consists of an investing serous, and 
a fibro-elastic coat, which enclose the proper substance of the 
spleen. 

The substance of the spleen consists of a soft, pulpy mass, of 
a reddish-brown color, which is contained in meshes of fibro-elas- 
tic tissue, derived from the elastic coat of the spleen, since that 
coat is prolonged into the interior of the organ as sheaths upon 



CONTENTS OF EA CH REGION. 



535 



its vessels. This pulpy mass is perceived, by the microscope, 
to consist of the following elements ; 

1st. Malpighian corpuscles. 
2d. Colored elements. 
3d. Colorless elements. 

The Malpighian corpuscles are whitish bodies, which vary from 
one twenty-fifth to one-sixtieth of an inch in size, and are devel- 
oped principally upon the arteries. The larger ones are percep- 
tible to the naked eye. 

The colored elements are composed of free blood corpuscles, pig- 
ment granules, and crystalline bodies whose composition resembles 
haematin. 

The colorless elements consist of cells, with and without nuclei, 
free nuclei, and finely granulated matter of an albuminous char- 
acter. 

The VESSELS of the spleen comprise the splenic artery and its 
branches, the splenic vein, and the lymphatics of that organ. 

The splenic artery is very tortuous and of large size. It 
divides, at the hilum of the spleen, into five or six branches 
which supply the various portions of the organ. Some of its 
branches open into spaces in the substance of the spleen, called 
lacunce, while others open directly into veins. 

The splenic vein carries the blood from the spleen, and assists 
in forming the portal vein. 

The lymphatics of the spleen open into the thoracic duct. 

The nerves are derived from the solar plexus, the semi-lunar 
ganglia, and the right pneumogastric nerve. 

REGIONS OF THE ABDOMEN. 

The abdomen is usually described as consisting of three zones 
and nine distinct regions. The three zones of the abdomen are 
represented by describing two horizontal lines across the anterior 
surface of the abdomen, which shall respectively join the highest 
points of the crests of the two ilia with each other, and the two 
cartilages of the ninth pair of ribs. 

The two lines, which subdivide these three zones, and thus 
form nine spaces or regions, descend, upon either side, from the 
cartilage of the eighth rib to the middle of Pou part's ligament. 

The spaces or regions, situated at the sides of the trunk, are 
named as follows, from above downwards. 

The two hypochondriac regions. 
The two lumbar regions. 
The two iliac regions. 



536 



REGIONS OF ABDOMEN. 



The spaces, in the middle line of the abdomen^ are named as 
follows, from above downwards : 

The epigastric region. 
The umbilical region. 
The hypogastric region. 
The parts contained within these various regions are as fol- 
lows. 



Right Hypochondriac. 
Ascending part of duodenum. 
Hepatic flexure of colon. 
Right lobe of liver. 
Gall bladder. 



Left Hypochondriac. 
Cardiac end of stomach. 
Splenic flexure of colon. 
Left lobe of liver. 
Spleen. 



Upper half of right kidney and its capsule. Upper half of left kidney and its capsule. 



Right Lumbar. 
Descending part of duodenum. 
Lower half of right kidney. 
Convolutions of small intestine. 
Head of pancreas. 
Ascending colon. 



Left L^umbar. 
Descending colon. 
Lower half of left kidney. 
Convolutions of small intestine. 



Right Lliac. 
Caecum. 
Right Ureter. 
Right spermatic vessels. 
Small intestine. 



Left Lliac. 
Sigmoid flexure of colon. 
Left ureter. 

Left spermatic vessels. 
Small intestine. 



Epigastric. 
Stomach. 
Left lobe of liver. 
Aorta. 

Inferior vena cava. 
Vena azygos major. 
Thoracic duct. 
Semilunar ganglia. 
Coeliac axis. 



Umbilical. 
Transverse colon. 
Body of pancreas. 
Transverse part of duodenum. 
Aorta. 



Hypogastric. 
Convolutions of small intestine. 
The uterus (in pregnancy). 
The normal bladder, in children. 
The distended bladder, in adults. 



CAR T1LA GES OF LAR YNX. 537 



THE LARYNX. 

The larynx is the essential organ of voice. It is composed of 
cartilages, united by ligaments, moved by muscles, lined with a 
mucous membrane, and supplied by vessels and nerves. 

Cartilages. 

The cartilages which compose the larynx are nine in number, 
three single and three pairs. 

Single cartilages. Pairs of cartilages. 

Thyroid cartilage. Arytenoid cartilages. 

Cricoid cartilage. Cuneiform cartilages. 

Epiglottis. Cornicula laryngis. 

The THYROID CARTILAGE resembles a shield in form and is 
composed of two quadrilateral plates or alee, joined together, in 
front, at an acute angle ; the highest part of which junction is called 
the pom u m Adam i. 

To its outer surface, are attached three muscles, viz., the sterno- 
thyroid, the thyro-hyoid, and the inferior constrictor muscles. 

To its inner surf ace , are attached the true and false vocal cords, 
the apex of the epiglottis, the thyro-epiglottic ligament, and the 
thyro-arytenoid and the thyro-epiglottidei muscles. It is covered 
by mucous membrane. 

To its upper border, which is irregularly curved, is attached 
the thyro-hyoid membrane. 

To the lower border, which is shorter and less curved than the 
upper, is attached the crico-thyroid membrane and the crico-thy- 
roid muscle. 

The posterior border of each ala affords attachment to the stylo- 
pharyngeus and the palato-pharyngeus muscles. Its upper and 
lower extremities are called the superior cornu and the inferior 
cornu. 

The superior cornu affords attachment to the thyro-hyoid lig- 
ament. 

The inferior cornu articulates with the cricoid cartilage and 
thus affords a point of motion between the thyroid and cricoid car- 
tilages. This capability of motion allows of the relaxation and 
tightening of the vocal cords, when the crico-thyroid muscles act. 

The CRICOID CARTILAGE is shaped like a ring, and is broad be- 
hind and narrow in front. It is thicker and stronger than any of 
the cartilages of the larynx. 



538 • ORGAN OF PHONATIO.Y. 

To its outer border, are attached the crico-arytenoideus muscle, 
and the longitudinal fibres of the oesophagus. This border affords 
articulation also for the inferior cornu of each ala of the thy- 
roid cartilage. 

The lower border is connected with the first ring of the 
trachea. 

The upper border affords attachment, in front and at its sides, 
to the crico-thyroid membrane and the crico-arytenoidei laterales 
muscles ; and it also presents, at its posterior part, two oval facets 
for its articulation with the arytenoid cartilages. 

The cricoid cartilage is a valuable surgical guide to the air 
passage, since it is always perceptible even in fat necks. It cor- 
responds to the level of the lower border of the fifth cervical 
vertebra. It is also of surgical value, in affording a guide to the 
point of crossing of the omo-hyoid muscle over the common carotid 
artery, since a horizontal line drawn across the neck on a level 
with this cartilage will cross the line of the carotid at the same 
point. 

The ARYTENOID cartilages are two in number and resemble 
in their form a truncated pyramid. They rest upon the posterior 
portion of the upper border of the cricoid cartilage, upon which 
they are capable of motion. 

Each cartilage presents for examination three surfaces, a base 
and an apex. 

The anterior surface affords attachment to the false vocal cord. 

The posterior surface affords attachment for the arytenoideus 
muscle. 

The internal surface is covered with mucous membrane and 
looks towards the corresponding surface of the opposite car- 
tilage. 

The base presents a smooth concave depression for articulation 
with the cricoid cartilage, and also two projections, which are called 
the anterior and posterior angles of the arytenoid cartilage. 

The anterior angle is long and pointed, and affords attach- 
ment for the true vocal cord and for the thyro-arytenoideus 
muscle. 

The posterior angle is short and rounded, and affords attachment 
for the crico-arytenoideus lateralis and the crico-arytenoideus pos- 
ticus muscles. 

The apex affords articulation for the cartilage of Santorini. 

The CORNICULA LARYNGIS or the CARTILAGES of SANTORINI 
are two small nodules of yellow elastic cartilage which articulate 
with the apices of the arytenoid cartilages. 



MUSCLES OF LAR YNX. 539 

The CUNEIFORM CARTILAGES or CARTILAGES of WRISBERG 
are two small rods of yellow elastic cartilage which are contained 
in the free border of the aryteno-epiglottidean folds. 

The EPIGLOTTIS is a flat lamella of yellow elastic cartilage, 
which resembles a leaf in shape, and which is connected, at its 
pointed extremity, with the angle of the thyroid cartilage and 
with the base of the tongue and the hyoid bone. It presents 
for examination an apex, a base, an anterior surface, a posterior 
surface, and two lateral margins. 

The apex is attached to the angle of the thyroid cartilage by 
the thyro-epiglottidean ligament. 

The base is unattached, and is broad and rounded. 

The anterior surface is attached, at its lower part, to the hyoid 
bone, by the hyo-epiglottic ligament ; and, higher up, to the 
tongue, by the three glosso-epiglottidean folds. Its upper part 
is unattached and curves over the base of the tongue. 

The posterior surface covers the superior aperture of the 
larnyx, when the bolus of food is passing through the pharynx. 
It presents numerous small depressions, in which are lodged 
mucous glands. 

The lateral margins are connected to the arytenoid cartilages 
by the aryteno-epiglottidean folds. 

Muscles. 

The muscles of the larynx are divided into two sets as fol- 
lows : 

Muscles of the glottis. Muscles of the epiglottis. 

Crico-thyroid. Thyro-epiglottideus. 

Thyro-arytenoid. Aryteno-epiglottideus inferior. 

Crico-arytenoid lateralis. Ayrteno-epiglottideus superior. 
Crico-arytenoideus posticus. 
Arytenoideus. 

ORIGIN AND INSERTION. 

Crico-Thyroid. 
Origin. 

From the front and sides of the cricoid cartilage. 
Insertion. 

Into the lower border and inferior cornua of thyroid 
cartilage. 
Nervous supply. 

The superior laryngeal nerve. 



540 ORGAN OF PH0NATI0N. 

Action. 

By tilting the thyroid cartilage forwards, it elong- 
ates and tightens the vocal cords. 

Thyro- Arytenoid. 
Origin. 

From the lower part of the receding angle of the 
thyroid cartilage, and the posterior surface of the 
crico-thyroid membrane. 
Insertion. 

Into the anterior surface, and the internal angle of 
the base of the arytenoid cartilage. 
Nervous supply. 

The recurrent laryngeal nerve. 
Action. 

By drawing the arytenoid cartilage forwards, it 
shortens and relaxes the vocal cords. 

Crico-Arytenoid Lateralis. 
Origin. 

From the side and upper border of the cricoid car- 
tilage. 
Insertion. 

Into the external or posterior angle of the arytenoid 
cartilage. 
Nervous supply. 

The recurrent laryngeal nerve. 
Action. 

By rotating the arytenoid cartilages, it approximates 
the anterior angles of these cartilages, and thus closes 
the opening of the glottis. 

Crico-Arytenoid Posticus. 
Origin. 

From the posterior surface of the cricoid cartilage. 
Insertion. 

Into the external or posterior angle of the aryten- 
oid cartilage. 
Nervous supply. 

The recurrent laryngeal nerve. 
Action. 

By rotating the arytenoid cartilages, it separates 
the anterior angles of those cartilages, and thus opens 
the glottis. 






MUSCLES OF LAR YNX. 



541 



Arytenoid. 

This is a single muscle, and is situated in the median line of 
the larynx between the two arytenoid cartilages. 

Origin. 

From the posterior surface and outer border of 
either arytenoid cartilage. 
Insertion. 

By oblique and transverse fibres, into the opposite 
cartilage. 
Nervous supply. 

From two sources, viz, 9 the superior and the recur- 
rent laryngeal nerves. 
Action, 

By approximating the arytenoid cartilages, it closes 
the glottis, especially at its posterior part. 

Thyro-Epiglottideus. 
Origin. 

From the inner surface of the thyroid cartilage, ex- 
ternal to the point of origin of the thyro-arytenoid 
muscle. 
Insertion. 

Into the margin of the epiglottis and the aryteno- 
epiglottidean fold. 
Nervous supply. 

The recurrent laryngeal nerve. 
Action. 

To depress the epiglottis and to create compression of 
the sacculus laryngis. 

Aryteno-Epiglottideus Inferior. 
Origin. 

From the arytenoid cartilage, just above the false 
vocal cord. 
Insertion. 

Into the margin of the epiglottis. 
Nervous supply. 

The recurrent laryngeal nerve. 
Action. 

To depress the epiglottis, and to assist in compressing 
the sacculus laryjigis. 

Aryteno-Epiglottideus Superior. 
Origin. 

From the apex of the arytenoid cartilage. 



542 ORGAN OF PHONA TION. 

Insertion. 

Into the aryteno-epiglottidean fold. 
Nervous supply. 

The recurrent laryngeal nerve. 
Action. 

To constrict the superior aperture of the larynx 

during the second act of deglutition. 

Of these muscles, the arytenoideus and the thyro-epiglottideus 

are situated in the median line, while the other muscles are 

spread out upon those surfaces of the cartilages of the larynx 

which are not situated in the median line of the body. 

Ligaments. 

» 

The ligaments of the larynx may be divided into two sets as 
follows : 

Extrinsic Ligaments. Intrinsic Ligaments. 

Thyrohyoid membrane. Crico-thyroid membrane. 

Lateral thyro-hyoid ligaments. Hyo-epiglottic ligament. 

Crico-thyroid capsular ligaments. 

Posterior crico-arytenoid ligaments. 

Thyro-epiglottic ligament. 

Crico-arytenoid capsular ligaments. 

It will thus be perceived that the three extrinsic ligaments of 
the larynx connect the organ with the hyoid bone, and that the 
six intrinsic ligaments serve to bind the component parts of the 
organ together. The names which are applied to the various lig- 
aments indicate the parts which they connect. 

The lateral thyro-hyoid ligaments connect the superior cornua 
of the thyroid cartilage to the hyoid bone. 

The thyro-hyoid membrane connects the upper border of the 
thyroid cartilage to the hyoid bone. 

The crico-thyroid membrane connects the inferior border of the 
thyroid cartilage with the cricoid cartilage. 

The capsular ligaments enclose the articulations between the 
thyroid and the cricoid cartilages on either side, and also the 
articulations between the cricoid cartilage and the two arytenoid 
cartilages. 

The posterior crico-arytenoid ligaments connect the bases of the 
arytenoid cartilages with the posterior surface of the cricoid 
cartilage. 

The thyro-epiglottic ligament connects the apex of the epiglottis 
with the receding angle of the thyroid cartilage. 

The hyo-epiglottic ligament connects the anterior surface of the 
epiglottis with the upper border of the hyoid bone. 



vessels and nerves of larynx. 543 

Cavity of the Larynx. 

The interior of the larynx is divided into two portions, by 
the margins of the true vocal cords, and the space between the 
arytenoid cartilages. This opening is termed the rima glottidis, 
and measures, in the adult, from three-quarters of an inch to an 
inch in length. The shape of this opening varies, since it is 
affected by all the muscular efforts required in respiration and in 
the production of sound. During tranquil breathing, it is trian- 
gular in shape with its base directed backwards, while, in violent 
respirations, it is lozenge-shaped, and, when sound is produced, it 
is transformed into a narrow slit. 

The true vocal cords lie below the false vocal cords, and con- 
sist of strong bands of yellow elastic tissue, which is continuous 
with the crico-thyroid membrane, and which is in relation with 
the thyro-arytenoideus muscle. They are inserted into the an- 
terior angles of the arytenoid cartilages, and the receding angle 
of the thyroid cartilage. 

The superior aperture of the larynx is triangular in form and is 
bounded, in front, by the epiglottis, and, upon either side, by the 
aryteno-epiglottidean folds. 

The false vocal cords are situated higher up in the larynx 
than the true vocal cords, and extend from the receding angle of 
the thyroid cartilage to the anterior surface of the arytenoid 
cartilages. 

In making an incision through the crico-thyroid membrane, 
the vocal cords are liable to be wounded, and the direction of the 
incision should therefore be transverse, and as near to the upper 
border of the cricoid cartilage as possible. 

The space, which exists upon either side, between the true and 
the false vocal cords is called the ventricle of the larynx. 

A space exists between the thyroid cartilage and the superior 
vocal cord, called the sacculus laryngis, which is a prolongation 
of the ventricle of the larynx, and which is covered by the thyro- 
epiglottideus and the two thyro-arytenoid muscles. It contains 
the openings of a large number of mucous glands, whose secretion 
serves to lubricate the true vocal cords. 

Mucous Membrane. 

The mucous membrane of the larynx is continuous with that 
of the pharynx and of the trachea. It is thin and oi' a pale pink 
color, and is covered, below the level of the superior vocal cords, 
and also, in front, as high as the middle of the epiglottis, with 



544 



ORGAN OF PHONA TION. 



ciliated epithelium, and, in the remaining portion of the larynx, 
with squamous epithelium. 

The glands of this mucous membrane are of a simple tubular 
and also of a conglomerate character. A large collection of 
glands, called the arytenoid glands, exist in the aryteno-epiglot- 
tidean folds ; and, in the sacculus laryngis, some sixty separate 
glands exist. 

Vessels. 

The vessels include branches of the superior thyroid and the 
inferior thyroid arteries, the superior, middle, and inferior thyroid 
veins, and lymphatic vessels. 

Nerves. 

The nerves comprise the superior laryngeal and the inferior or 
recurrent laryngeal nerves, both of which are derived from the 
pneumogastric nerve, and filaments from the sympathetic. 

The superior laryngeal nerve enters the cavity of the larynx 
through a hole in the thyro-hyoid membrane, and is distributed 
to the mucous lining of the organ and to the crico-thyroid and the 
arytenoid muscles. 

The inferior or recurrent laryngeal nerve enters the cavity of 
the larynx, at its posterior portion, passing behind the articula- 
tion of the inferior cornu of the thyroid cartilage and the exter- 
nal surface of the cricoid cartilage. It supplies all the muscles of 
pho?iation, with the exception of the crico-thyroid muscle. 



THE TRACHEA 545 



THE TRACHEA. 

The trachea is a cartilagino-membranous tube, which extends 
from the cricoid cartilage of the larynx, at a point corresponding 
to the $tk cervical vertebra, to the 3d dorsal vertebra, where it 
bifurcates into the right and left bronchus. It is rounded in its 
form, and is composed of cartilaginous rings connected together 
by a fibrous membrane. It is lined upon its interior surface with 
a mucous membrane, which is continuous with that of the larynx. 

The cartilages are usually twenty in number, and each forms 
two-thirds of a circle. They are supplied at their incomplete 
portion, which lies posteriorly, with muscular fibres, to which the 
name trachealis muscle is applied. 

The first and last of these cartilages present special character- 
istics. The lower edge of the last cartilage is prolonged downwards 
at its centre, and presents the openings of two imperfect rings 
which form the commencement of the bronchial tubes of either 
side ; while the first cartilage is thicker and broader than the rest. 

The fibrous membrane, which connects the cartilages of the 
trachea with each other, embraces both surfaces of each carti- 
lage by dividing into two layers, which unite with each other at 
its upper and lower border. 

The muscular fibres of the trachea are situated chiefly at its 
posterior portion, between the incomplete portion of the cartilagi- 
nous rings, and consist of a longitudinal and transverse set. 

The mucous membrane is pink in color, and is covered with 
columnar ciliated epithelium. 

The glands are of the conglomerate variety, and are found scat- 
tered beneath the mucous membrane, and also between the layers 
of the fibrous membrane which connects the cartilaginous rings. 

The arteries of the trachea are derived from the inferior thy- 
roid and the bronchial arteries, and the veins terminate in the 
thyroid plexuses and in the bronchial vein. 

The nerves are derived from the pneumogastric, the recurrent 
laryngeal, and the sympathetic. 

The length of the trachea is four and one-half inches. It 
corresponds to the length of the pharynx, and is one-half oi the 



5 46 OR GA XS OF R ESP IRA TIOX. 

length of the oesophagus, which fact may help the memory of 
the student, in recalling either of the three. 

The trachea is very deeply situated in the lower portion of 
the neck, and is reached with difficulty except at its upper part, 
since, in cases of extreme dyspnoea, the head is usually drawn 
forwards, and the approximation of the chin to the sternum 
shortens the working space for the Surgeon. In addition, the 
swelling of the thyroid veins, and the rigidity of the sternal mus- 
cles add to the difficulties of reaching the trachea. 

The distance between the lower border of the larynx and the 
upper border of the sternum is modified greatly by the position 
of the head, but it measures only one and a half inches in the 
normal attitude, and when the head is fully extended, three quar- 
ters of an inch is added. It will thus be perceived that only about 
eight rings of the trachea are above the sternum. 

The relations of the trachea within the neck and the thorax 
are important, and may be enumerated as follows : 

In front. 

The isthmus of the thyroid gland. 

The arteria thyroidea ima. 

The inferior thyroid vein. 

The remains of the thymus gland. 

The left vena innominata. 

The arch of the aorta. 

The arteria innominata and the left common carotid artery. 

The great cardiac plexus. 

The bifurcation of the pulmonary artery. 

The sternum, sternal muscles, fascia, and integument. 
Behind. 

The oesophagus. 

The ri^ht recurrent laryngeal nerve. 
Laterally. 

The lateral lobes of the thyroid gland. 

The common carotid arteries. 

The internal jugular veins. 

The pneumogastric and sympathetic nerves. 

The inferior thyroid arteries. 

The left recurrent laryngeal nerve. 

T ., ., ., . ,. -j I Ri^ht vena innominata. 

In the thorax on the right side. • r> - & u . , 

° | Right phrenic nerve. 

T .- .- ,, , r . , i Left subclavian artery. 

In the thorax on the left s.de. • Left ^^ ^^ 



THE BRONCHI, 547 



THE BRONCHI. 

The right and left bronchi commence at the bifurcation of 
the trachea, at a point corresponding to the ^d dorsal vertebra, 
and a little to the left of the median line of the spinal column. 

The right bronchus is wider than the left, and lies more hori- 
zontally. It is about one inch in length, and enters the root of 
the right lung on a level with the Ajh dorsal vertebra. In its 
course, it lies behind the superior vena cava and the right auricle 
of the heart, while the right pulmonary artery lies at first below 
it, but becomes anterior to it, before it enters the lung. The 
vena azygos major arches over it, passing from behind forwards. 

The left bronchus is the smaller of the two, is more oblique in 
its direction, and is nearly two inches in length. It enters the 
root of the left lung on a level with the $th dorsal vertebra. In 
its course, it passes beneath the arch of the aorta, and in front 
of the descending portion of the arch of the aorta, the oesophagus, 
and the thoracic duct. The pulmonary artery of the left side lies 
at first above it, and then in front of it. 

The bronchi present the same general appearance on section 
as does the trachea, since the cartilaginous rings are continued in 
the bronchi, even after they enter the substance of the lung. These 
rings are evidently intended by Nature as a source of protection 
against any outside pressure which might produce impairment to 
the free entrance of air into the lung. 

The bronchi, immediately after their entrance into the lung, 
divide into large primary divisions, which, in the right lung, are 
two in number, and, in the left lung, are three in number. This 
point may be easily remembered by recalling the fact that the 
primary divisions of the bronchial tubes are in antagonism to the 
respective number of lobes which each lung presents, since the 
right lung has three lobes and two main bronchi; while the left 
lung has two lobes and three main bronchi. 

The cartilaginous rings of the bronchi extend to the second or 
third bifurcation of the bronchus within the lung substance, when 
the rings give place to plates of cartilage, scattered within the 
walls of the bronchial tubes. 

These plates of cartilage disappear altogether when the tubes 
reach a diameter of about one-thirtieth to one-fiftieth of an inch, 



548 



ORGANS OF RESPIRA TION. 



since they are no longer required as a protective measure against 
obstructed entrance to air. 

Within the substance of the lung th© bronchial tubes divide 
and subdivide dichotomously until they reach a diameter of about 
one-fiftieth of an inch, when they penetrate the various lobules 
of the lung, and, since they then pass between the air cells, they 
are called intercellular passages. 

The bronchial tubes, within the substance of the lung are 
usually found to be placed between corresponding branches of the 
pulmonary artery and vein. 

THE LUNGS. 

The essential organs of respiration are contained within the 
cavity of the thorax and are characterized by their light density, 
their porous structure, their crepitation on pressure, and their 
elasticity. 

At the time of birth, their color is of a pinkish white, but, in 
the adult, a mottled grey color is developed, and, as age advances, 
the mottling becomes darker and frequently almost black. 

The lungs present' for examination an outer and an inner sur- 
face, an anterior and a posterior border, a base, and an apex. 

The outer surface is convex, and, at its posterior portion ex- 
tends deeper in the cavity of the chest than in its anterior portion. 
Upon either side, may be perceived a deep fissure which extends 
obliquely downwards and forwards from the region of the apex 
towards the base ; and, in the right lung, another fissure which 
extends obliquely upwards and forwards from about the central 
point of the fissure above mentioned. These fissures divide the 
lungs into their respective lobes. The left lung is divided into 
two lobes, while the right lung is divided into three. The lower 
lobes of both lungs are of large size. In the right lung, the mid- 
dle is the smallest of the three lobes. The outer surface of each 
lung lies in close relation with the parietes of the chest and is sep- 
arated from it by its pleural investment. 

The inner surface of the lung is concave, and, upon the left 
side, is deeply excavated in order to afford a space for the heart 
and the pericardium. This surface of the lung assists in forming 
the space called the middle mediastinum of the chest, in which are 
contained the heart, the pericardium, all the great vessels con- 
nected with the heart, the phrenic nerves, and the bifurcation of 
the trachea. 

The anterior border of the lung is shorter than the posterior 



THE LUNG. 



549 



border and comes in contact with the corresponding border of the 
opposite lung at about the middle of the sternum ; but, below 
that point, the two diverge and leave a portion of the pericardium 
exposed. 

The posterior border of the lung is more vertical in direction, 
and is longer than the anterior border. It differs also in being 
thicker and more rounded than the anterior. 

The base of each lung is broad, concave, and directed obliquely 
downwards and backwards. It is in relation with the diaphragm, 
and its circumference is received into the groove formed between 
the diaphragm aud the internal surface of the ribs. The base of 
the left lung descends lower in the thorax than that of the right 
lung, since the liver is situated upon the right side. The upper 
border of the liver, therefore, although it corresponds to the 
level of the ninth dorsal vertebra at its highest point, would still 
be wounded were any injury received in the anterior aspect of 
the chest, which caused perforation at the space between the 
sixth and seventh ribs, provided the intervening lung were like- 
wise perforated. 

The apex of each lung passes up into the root of the neck for 
about an inch above the first rib, where it lies in close relation 
with the first and second portions of the subclavian artery, and 
under the cover of the scaleni muscles. 

The ascent of the apex of the lung into the neck has a bear- 
ing upon the diagnosis of tuberculous disease, which usually is 
first developed in this region of the lung; and also upon the di- 
agnosis of injuries received at the root of the neck, since, if the 
lung be involved, a peculiar crackling sound, due to the infiltra- 
tion of air into the surrounding tissues, will often, be detected. 

The root of the lung is that portion where the bronchus, the 
pulmonary and bronchial vessels, the lymphatic vessels, and the 
nerves, derived from the pneumogastric and sympathetic plexuses, 
are afforded a means of entrance into the lung. These parts 
are bound together by areolar tissue, and are enclosed in a pro- 
tective covering formed by the pleura. The following relations, 
between important structures, exist within the root of the lung 
and are deserving of special mention. 

A. From before, backzvards. 

1. The pulmonary veins, and the anterior pulmonary 

plexus. 

2. The pulmonary artery. 

3. The bronchus, with its vessels, lymphatics, and the 

posterior pulmonary plexus. 



55o 



ORGAN OF RESPIRA TION. 



These relations are the same upon each side of the 
body, and may be, perhaps, more easily remembered 
by the initial letters of the more important structures, 
viz., V. A. B. 
B. From above, downwards. 

{Bronchus. 
Pulmonary artery. 
Pulmonary veins. 

{Pulmonary artery. 
Bronchus, 
Pulmonary veins. 

Jt will thus be perceived that the relations from 

above, downwards differ on the two sides of the body 

and may be represented by the initial letters of B. A. 

V. and A. B. V. This difference is produced by the 

obliquity of the left bronchus, which falls below the 

level of the artery upon the left side of the body. 

The root of the right lung lies posteriorly to the superior vena 

cava and the right auricle of the heart, and the vena azygos major 

arches over it from behind forwards. 

The root of the left lung passes beneath the arch of the aorta, 
and in front of the descending portion of the arch, the oesophagus 
and the thoracic duct. 

The root of each lung has also in front of it the phrenic nerve, 
and behind it the pneumogastric nerve. 

STRUCTURE OF THE LUNG. 

The intimate structures of the lungs may be grouped under 
three main divisions, viz. : 

The parenchyma. 

The serous coat or the pleura. 

The subserous areolar tissue. 

Parenchyma of the Lungs. 

The parenchyma, or the true structure of the lungs, embraces 
the following structures: 

i. Bronchial tubes. 

2. The lobules of the lung. 

3. The pulmonary vessels. 

4. The bronchial vessels. 

5. The lymphatic vessels. 

6. The nerves of the lung. 

7. The connective tissue between the lobules. 



THE LUNG. 551 

The bronchial tubes have already been described, as sub- 
divisions of the main bronchus. 

The lobules of the lung are arranged upon the terminal extrem- 
ities of the smaller bronchial tubes, like leaves upon the twigs of 
a tree. Each lobule is, in its form and general appearance, a 
minature lung, which is pyramidal in its outline, and whose base 
is directed outwards. The average size of each lobule is about 
one-twelfth of an inch. It is usually divided, in its interior, into 
compartments, called air cells, whose diameters vary from one 
seventy-second to one two-hundredth of an inch. 

The interior of each lobule reveals not only the different com- 
partments, called the air cells, but also communicating passages 
between these air cells, which are continuations of the bronchial 
tubes, and which are called the intercellular passages of the 
lobule. These passages vary from four to nine in number to each 
lobule, and their walls are characterized by saccular dilatations. 
They differ in their construction from the bronchial tubes in that 
they possess no cartilage, muscular fibres, or glands, and in that 
the epithelium which invests their walls is of the squamous variety 
in place of the ciliated variety, which lines the bronchial tubes. 

The air cells, or alveoli, are small chambers which are con- 
tained within the lobules of the lung, and which are separated 
from each other by thin septa, named alveoli. The variations in 
their size has been already mentioned. Each air cell consists of 
the following component parts, in their order from within out- 
wards, which enter into the construction of the walls. 

1. Pavement epithelium. 

2. A basement membrane. 

' Pulmonary arteries. 
Pulmonary veins. 
Bronchial arteries. 
Bronchial veins. 
Nervous plexus. 
.. Lymphatic vessels 
4. Elastic tissue of the lungs. 

These four layers may be compared, in order to assist mem- 
ory, to the construction of the ordinary partitions between the 
rooms of a dwelling, where the paper represents the epithelial 
covering ; the plaster, the basement membrane ; the laths, the six 
plexuses ; and the brickwork behind all, the elastic tissue of the 
lobule. 

The pulmonary vessels comprise the branches of the pulmonary 
artery, which carries blood from the right ventricle, and the pul- 



3. Six plexuses. 



552 ORGAN OF RESPIRA TION. 

monary veins, which empty their blood by four large orifices, into 
the left auricle of the heart. This set of vessels has little if any- 
thing to do with the nutrition of the lung substance, but is in- 
tended alone for the purpose of promoting oxygenation of the 
blood, after it has become impregnated with carbonic acid by 
its circulation through the systematic capillaries. 

The bronchial vessels comprise the bronchial arteries, whose 
main trunks are derived from the thoracic aorta ; and the bronch- 
ial veins, which empty into the vena azygos, upon the right side, 
and, upon the left side, into the left superior intercostal vein. 
These vessels supply the lung substance with nutrition, and have 
nothing to do with the process of oxygenation. 

The lymphatic vessels are arranged in two sets, called the su- 
perficial and the deep set, and terminate in the bronchial glands. 

The nerves are derived from the anterior and the posterior 
pulmonary plexuses, which are formed by filaments from the 
pneumogastric nerves and from the sympathetic. 

The cellular tissue, between the lobules of the lung, serves to 
bind the component parts of the lung together. In the foetus 
this tissue is imperfectly developed, so that the lobules of the 
lung can be easily separated from each other, but, in the adult, 
such a separation is impossible. In this tissue, as age advances, 
a peculiar coloring matter, composed of animal matter and car- 
bon, is deposited. 

THE PLEURA. 

The serous covering of the lung consists, like other serous 
membranes, of a shut sac, and invests the entire lung as well 
as its root. As each lung has a pleura of its own, the two sacs 
are distinct and separate, although they meet at the point of junc- 
tion of the anterior borders of the two lungs, which corresponds 
with the middle of the sternum. 

Each pleura may be traced as two folds over the outer and 
inner surfaces, the apex, the base, and the root of the lung 
which it invests. It is thin and adherent, where it invests the 
diaphragm, and where it comes in direct contact with the lung 
substance ; and it is thicker and less adherent, where it lines the 
parietes of the chest. 

The reflection of the pleura, which binds the root of the lung 
to the upper surface of the diaphragm, is called the ligamentum 
pulmonis latum. 

That portion of the pleura, which invests the apex of the lung, 



THYROID GLAND. 



553 



is brought in close relation with the subclavian artery, and the 
scaleni muscles. 

The arteries of the pleurae are derived from the following 
sources. 

1. The intercostal arteries. 

2. The internal mammary arteries. 

3. The phrenic arteries. 

4. The inferior thyroid arteries. 

5. The pericardiac arteries. 

6. The bronchial arteries. 

The veins, which return the blood from the pleurae, follow the 
same general course as the arteries. 

The lymphatic vessels of the parietal layers of the pleurae, join 
with those of the mediastina and the walls of the thorax ; while 
those of the visceral layers empty into the lymphatic vessels of 
the lung. 

The nerves, which supply the pleurae, are derived from the two 
pulmonary plexuses, which lie in relation with the roots of the 
lungs ; a few filaments from the phrenic nerves and from the 
sympathetic, however, directly supply it. 



THE THYROID GLAND. 

This gland lies in front of the upper part of the trachea, 
and at the sides of the oesophagus, the lower portion of the 
pharynx, and the larynx. It is soft in consistence, brownish in 
color, and is very vascular. Its average weight is about one and 
a half ounces, although it is usually somewhat larger in females 
than in males. 

This gland, at its lateral portions, covers entirely or in part, 
the following structures. 

1. The common carotid arteries. 

2. The inferior thyroid arteries. 

3. The internal jugular veins. 

4. The pneumogastric nerves. 

5. The recurrent laryngeal nerves. 

6. The filaments of the sympathetic. 

The thyroid gland presents for examination the following 
points of interest. 

1. Two lateral lobes. 

2. A connecting band called "the isthmus." 

3. A small lobe called •* the pyramid." 



554 



THYMUS GLAND. 



The lateral lobes are broader below than above, since they be- 
come constricted at the isthmus of the gland. They are about 
two inches long, at their broadest part, and three-quarters of an 
inch in depth. They extend from the inferior cornua of the thy- 
roid cartilage of the larynx, to the level of the fifth cartilage of 
the trachea. 

The isthmus of the thyroid gland connects the two lateral 
lobes and lies transversely across the trachea on a level, in the 
majority of subjects, with the third or the fourth ring, although 
the line of crossing varies. 

The pyramid or third lobe of the thyroid gland is often absent, 
but, when present, it is situated between the hyoid bone and the 
isthmus, to both of which it is often attached, although it may 
be connected to the lateral lobe of either side. 

The thyroid gland is enclosed within a capsule, and is com- 
posed of a multitude of small closed vesicles, which are flattened 
somewhat by pressure, and which are connected together by are- 
olar tissue. It has no duct, and its function is not positively 
known. 

The arteries are remarkable for their size, and for their fre- 
quent anastomoses. 

The veins open into the superior, the middle, and the inferior 
thyroid veins. 

The nerves are derived from the middle and the inferior cer- 
vical ganglia of the sympathetic. 

THE THYMUS GLAND. 

The thymus gland is a soft lobulated mass of a pinkish-grey 
color, which is situated in the upper part of the anterior medias- 
tinum, and in the lower part of the neck, at the time of its most 
extensive development, which occurs at the end of the second 
year. 

When fully developed, this gland weighs about half an ounce, 
and measures nearly two inches in length, but, as atrophy soon 
begins, it decreases rapidly in size, and, by the age of puberty, 
almost all signs of glandular structure have disappeared. 

The thymus gland, when fully developed, presents a base, an 
apex, an anterior surface, and a posterior surface. 

The base rests upon the upper portion of the pericardial sac. 

The apex often reaches to the lower border of the thyroid 
gland. 

The anterior surface is convex, and is in relation with the two 



THE KIDNEY. 555 

upper pieces of the sternum, the internal mammary arteries and 
veins, and the sterno-thyroid and sterno-hyoid muscles. 

The posterior surface is concave, and rests upon the pericardi- 
um, the arch of the aorta, the left innominate vein, the four large 
arterial trunks given off from the upper portion of the transverse 
arch of the aorta, and the anterior aspect of the trachea. 

The intimate structure of the thymus gland presents the fol- 
lowing points of interest. 

1. The investing capsule. 

2. The central cavity or reservoir. 
4. The lobules. 

The capsule sends trabecular into the substance of the gland, 
and invests its entire outer surface. 

The reservoir, the central cavity, is of large size, and pene- 
trates into the lobes and lobules of the gland. 

The lobules vary in size from a pin's head to that of a pea, 
and are bound together by areolar tissue. They are divided 
into primary and secondary lobules, the latter of which are con- 
tained within the former, and, of necessity, are of smaller size. 

The arteries of the gland are derived from the following 
sources. 

1. The internal mammary arteries. 

2. The inferior thyroid arteries. 

3. The superior thyroid arteries. 

4. Occasional branches from the common carotid and subcla- 

vian arteries. 

The veins open into the left innominate vein, and into the 
thyroid veins. 

The nerves are derived from the pneumogastric nerves and the 
sympathetic system. 

THE KIDNEY. 

The kidneys are two glandular organs, which are situated upon 
either side of the body, in the back part of the abdominal cavity. 
They extend from the nth rib to the level of the crest of the 
ilium, although the right kidney usually lies somewhat lower 
than the left, on account of the liver. 

The kidneys are each about four inches long, two inches broad 
and one inch in thickness. They each present for examination 
two surfaces, two borders, and two extremities. 

The anterior surface is in relation, upon the right side, with 
'the right lobe of the liver, the descending duodenum, and the as- 



556 THE URINARY ORGANS. 

cending colon ; while, upon the left side, it is in relation with the 
tail of the pancreas, the descending colon, and the lower portion 
of the spleen. This surface is convex, and is covered in part by- 
peritoneum. 

The posterior surface is flat, and is in relation with the crus of 
the diaphragm, the nth and 12th ribs, the psoas magnus muscle, 
the aponeurosis of the transversalis, and the quadratus lum- 
borum muscle. This surface is not covered with peritoneum. 

The superior extremity is the largest and the thickest of the 
two extremities of the organ, is directed inwards, and is capped 
by the suprarenal capsule. 

The inferior extremity is small, flattened in shape and is 
directed outwards. It corresponds nearly with the crest of the 
ilium. 

The outer border is convex, and is directed outwards and 
backwards. 

The inner border is concave, is directed forwards and down- 
wards, and is marked by a depression or fissure, called the hilum 
of the kidney, which leads into the cavity of the organ and which 
gives passage, from before backwards, to the renal vein, the renal 
artery, and the ureter. 

The kidney is enveloped in a fibrous capsule, which is thin, 
smooth, and firm, and which is loosely connected with the sub- 
stance of the organ. 

On a longitudinal section of the organ being made, the kidney 
is perceived to consist of two portions, which differ in their color, 
appearance, and general structure. 

The inner portion, which is called the medullary portion of the 
kidney, is arranged in the form of pyramids, from eight to eighteen 
in number, whose bases are directed towards the surface of the 
organ and whose apices are directed inwards and terminate as 
little projections, to which the name papillce is applied, into the 
cavity of the kidney. 

This portion of the kidney is dark in color, striated in appear- 
ance, and of dense consistence ; and is formed by the straight 
uriniferous tubes, (the tubes of Bellini), and by looped uriniferous 
tubes, (the tubes of Henle). Each of the large pyramids of the 
medullary substance is called a "pyramid of Malpighi," and, as 
before stated, these pyramids vary from eight to eighteen to each 
kidney. 

The outer portion of the kidney, which comprises about three- 
fourths of the entire organ, is termed the cortical substance of the 
kidney. It is soft in consistence, reddish in color, and granular in 



THE KIDNE Y. 



557 



appearance. It sends prolongations between each of the pyramids 
of Malpighi, which prolongation are called the columns of Bert in. 
The cortical substance of the kidney is found to consist of the fol- 
lowing component parts : 

1. Uriniferous tubes, of various forms. 

2. Malpighian bodies or corpuscles. 

3. Blood-vessels. 

4. Nerves. 

5. Lymphatics. 

6. Connective tissue, (inter-tubular stroma). 

7. A granular matrix. * 

The varieties of URINIFEROUS TUBES, which are met with in 
the kidney, are named as follows : 

1. The convoluted tubes, so named from their twisted course. 
These tubes form the greater portion of the cortical substance of 
the kidney, and are continuous, at one extremity, with the Mal- 
pighian corpuscles, and, at the other extremity, with the looped 
tubes of Henle. 

The looped tubes of Henle are so called from the course which 
they take, and from their discoverer. They form an anastomosing 
link between the convoluted tubes and the straight uriniferous 
tubes, although an additional variety of tube is now believed to 
exist between these points, to which the name communicating 
tube has been applied. The tubes of Henle are subdivided into 
a descending and an ascending portion, since they form a loop 
extending into the medullary portion of the kidney. 

The straight uriniferous tubes are also called the " tubes of 
Bellini." They have been also named, when found in the corti- 
cal portion, the tubes of Ferrein. 

The tubes of Bellini compose the greater portion of the 
medullary substance of the kidney, and give to that portion 
of the organ the striated appearance, which is characteristic 
of it. 

The tubes of Ferrein are a direct extension of the straight tubes 
of Bellini upwards into the cortical portion of the kidney. They 
are generally arranged in the form of small pyramids, to which 
the name " pyramids of Ferrein " is applied. 

The Malpighian bodies or corpuscles are, in the majority of 
instances, a dilated extremity of a convoluted uriniferous tube, 
and average about one one-hundred and twentieth of an inch in 
diameter. They consist of an investing capsule, called the " cap- 
sule of Miiller''' and a tuft of blood-vessels, called the " Malpig 
hian tuft," 



558 URINAR Y ORGANS. 

The VESSELS of the kidney are derived from the renal artery 
and terminate in the renal vein ; but, as the circulation of the kid- 
ney has some points of special interest connected with it, a rapid 
enumeration of the parts, to which special names have been ap- 
plied, seems demanded. 

The renal artery first divides into four or five primary branches, 
and subsequently into as many subdivisions as there are columns 
of Bertin, into each of which two vessels enter. These vessels, at 
the base of each pyramid, join with their fellow of the opposite 
side, to form arterial arches over each pyramid. 

These arterial arches give off branches which ascend into the 
cortical portion of the kidney, and descending branches which sup- 
ply the pyramids with nutrition. 

Each ascending branch subdivides, along its entire course, into 
arteries, which go to the various Malpighian bodies, and which 
are called " afferent vessels!' 

Each afferent vessel forms, within the Malpighian body, an 
arterial tuft, called the "Malpighian tuft" 

The vessels of each Malpighian tuft again unite to form a 
single vessel called the " efferent vessel." The question of the 
arterial or venous character of the efferent vessel is not yet posi- 
tively decided. 

The efferent vessels of the various Malpighian tufts, after 
their escape from the capsule of Miiller, immediately break up 
into a venous plexus upon the convoluted portions of the uriniferous 
tubes. 

From these venous plexuses, veins ascend to the surface of 
the kidney, where they form stellate plexuses, called the stars of 
Verheyen. 

The veins of the kidney return in the same general way as the 
arteries entered, and therefore comprise both descending and as- 
cending veins, which assist in forming venous arcades. These 
subsequently form the primary veins of the kidney, which unite 
to form the renal vein. 

The blood which is distributed to the kidney passes, therefore, 
through the following named vessels before its exit from the organ. 

1. Renal artery. 

2. Primary branches of renal artery. 

3. Arterial arcades (over the bases of the pyramids). 

4. Ascending and descending branches. 

5. Afferent arteries. 

6. Malpighian tufts. 

7. Efferent vessels. 



THE URETER. 559 

8. Uriniferous plexuses. 

9. Stars of Verheyen, (venous plexuses). 

10. Ascending and descending veins. 

11. Venous arcades, (over bases of pyramids). 

12. Primary veins. 
12. Renal vein. 

The NERVES of the kidney are derived from the renal plexus 
and from the lesser splanchnic nerve. 

The lymphatics comprise a superficial and a deep set, and 
open into the lumbar glands. 



THE URETER. 

The ureter is the excretory duct of the kidney, and, by its 
upper or expanded portion, it forms the internal cavity of that 
organ. 

The pelvis of the kidney, which is but another name for the 
upper end of the ureter, may be subdivided into the following 
portions : 

The pelvis proper. 
The infundibula. 
The calices. 

The infundibula are large prolongations, usually three in num- 
ber, from the main cavity of the pelvis. 

The calices are smaller prolongations from the three infundi- 
bula, which vary from seven to thirteen in number, and which 
embrace the papillae of the kidney. They serve to collect the 
urine as it escapes from the small openings of the straight 
tubes of that organ, and to convey it to the ureter. 

The ureter is from sixteen to eighteen inches in length, and 
is of the diameter of an ordinary quill. As it passes downward to 
open into the bladder, near to its base, it bears an important sur- 
gical relation to the common iliac artery, to which vessel, in cases 
where its ligation is demanded, it is often used as a guide. 

The ureter, in all of its portions, has three coats, to which the 
names fibrous, muscular, and mucous coats are applied. 

The epithelium of the mucous coat is spheroidal in character 
and differs from that of the urethra, bladder, or the uriniferous 
tubes. This is an anatomical point of practical value, since, in 
cases of inflammatory diseases of the genito-urinary tract, the 
variety of epithelium detected in the urine is of great value in 
deciding upon the locality of the disease. 



560 URINARY ORGANS. 

SUPRA-RENAL CAPSULES. 

These are small crescentic bodies, of a yellowish-brown color, 
which lie upon the upper and front part of the kidney. They 
weigh about two drachms each. The left capsule is the largest 
and highest in its situation. 

They are ductless glands. They consist of a fibrous capsule, 
a striated cortical substance, an imperfectly developed medullary 
structure, blood-vessels, lymphatics, and nerves. 

They are supposed, by some, to be a part of the sympathetic 
system ; by others, to be a ductless gland only ; and by Kolliker, 
to perform both functions, the medullary part being the nervous 
portion, and the cortical part the glandular. 

THE BLADDER. 

The bladder differs in its situation in the two sexes ; and also 
in its situation and its shape, whether it be distended or empty. 

In the male, when empty, it is deeply situated behind the 
pubes and in front of the rectum ; while, in the female, it lies in 
front of the uterus and the vagina. 

The shape of the bladder is conical in children, and reaches a 
higher point within the pelvis than in the adult ; while the adult 
bladder is rounded in form, when moderately distended, and egg- 
shaped when fully distended. 

The male bladder, when distended, lifts the peritoneum for a 
distance of about two inches above the pubes, and thus affords a 
space where puncture or incision can be made without danger of 
injury to the peritoneum. 

The bladder presents for examination the following parts, 
namely : four surfaces, an anterior, a posterior, and two lateral 
surfaces, and an apex, a base, and a neck. 

The anterior surface is uncovered by peritoneum, and is in 
relation with the following structures. 
The pubes. 

The pubo-prostatic ligaments. 
The triangular ligament of the urethra. 
The anterior wall of the abdomen (in children and 
in adults, if distended). 

The posterior surface is separated, by the intestine, from the 
rectum, in the male, and, in the female, from the uterus. It is 
covered by peritoneum. 

The lateral surfaces are in relation with the following struc- 
tures: 



THE BLADDER. 



561 



The pelvic fascia. 

The obliterated hypogastric arteries. 

The ureters. 

The vasa deferent ia, (in the male sex). 

It is covered by peritoneum, above and behind the obliterated 
hypogastric arteries, while, in its other portions, it is destitute of 
such a covering, since it rests upon the pelvic fascia. 

The apex of the bladder is attached to the umbilicus by the 
urachus and the obliterated hypogastric arteries, and it is covered, 
behind that point, by the peritoneum. 

The base or fundus of the bladder is in relation, in the male 
sex, with the second portion of the rectum, while, in the female 
sex, the anterior wall of the vagina and the neck of the uterus is 
in relation with it. That portion of the male bladder, which is 
in close relation with the rectum, corresponds with a triangular 
space which is bounded as follows : 

In front, by the prostate gland. 
Laterally, by the vesiculae seminales. 
Behind, by the reflection of the peritoneum. 

The neck of the bladder is surrounded, in the male sex, by the 
prostate gland. In the erect position of the body, in both sexes, 
the neck of the bladder is the lowest part of that organ, and is 
directed downwards and forwards. 

The bladder has five true and five false ligaments, the latter 
of which are formed by reflections of peritoneum. These liga- 
ments may be enumerated as follows : 

True ligaments. False ligajnents. 

Two anterior or pubo-prostatic. Two posterior false ligaments. 
Two lateral ligaments. Two lateral false ligaments. 

Superior ligament or the urachus. Superior false ligament. 

The pubo-prostatic ligaments extend from the pubes to the 
prostate gland and the neck of the bladder. 

The lateral ligaments, of the true set, are formed by the pelvic 
fascia, and are attached to the sides of the prostate gland and the 
sides of the bladder. 

The superior ligament or the urachus consists of a fibro-mus- 
cular cord, which connects the apex of the bladder with the 
umbilicus. 

The posterior false ligaments contain the obliterated hypo- 
gastric arteries. 



562 URINARY ORGANS. 

The lateral false ligaments connect it with the sides of the 
pelvis. 

The superior false ligament is a reflection of peritoneum, 
over the urachus and the obliterated hypogastric arteries, to 
the region of the umbilicus. 

The COATS of the bladder are four in number, and are called, 
from without inwards, as follows : 

The serous coat. 
The muscular coat. 
The cellular coat. 
The mucous coat. 

The serous coat is formed by the peritoneum, and is deficient 
in certain portions of the organ. It is most marked upon the 
posterior surface, the sides, and the posterior portion of the base 
of the bladder. 

The muscular coat consists of three distinct sets of fibres dis- 
tributed over the entire organ, and two additional sets connected 
with the ureters. The former group are named, respectively, the 
external longitudinal fibres, the intermediate circular fibres, and 
the internal longitudinal or sub-mucous fibres. The two sets of 
fibres connected with the ureters comprise a transverse set, which 
connect the orifices of the tubes ; and the muscles of the ureters 
proper, which ' connect each tube with the middle lobe of the 
prostate gland. 

The cellular coat of the bladder is situated between the mus- 
cular and the mucous coats of that organ, and is most closely 
attached to the mucous coat. 

The mucous coat of the bladder is of a light color, and is loosely 
connected to the muscular coat, except at two specially designated 
localities within that organ, called the trigonum vesica? and the 
uvula vesica?. In cases where the muscular coat of the bladder 
has undergone changes, either of hypertrophy or of separation 
of its fibres, the mucous lining of the organ is thrown either into 
proportionate ridges or depressions, thus forming the so-called 
fasciculated bladder, and the sacculated bladder. 

The trigonum vesica? is a triangular space at the base of the 
interior of the bladder, which is distinguished by its pale color and 
the close intimacy which exists between its mucous and muscular 
coats. It is bounded as follows : 

In fro?it, by the urethral opening. 
Behind, by the orifices of the ureters. 
Laterally, by two folds of mucous membrane. 

This space corresponds to that portion of the bladder, which 



THE PENIS. 



563 



lies in intimate relation with the rectum, and it is in this space 
that puncture of the bladder, through the rectum, is performed ; 
since the close contact of the organs, and the almost entire 
absence of connective tissue, renders the escape of the urine, 
in other channels, difficult. 

The uvula vesica is an elevation of the mucous lining of the 
bladder, situated near to the mouth of that organ. It is sup- 
posed, by some of the more recent investigators, to assist in 
preventing the escape of the urine, by being lifted by the ante- 
rior fibres of the levator ani muscle, and thus applied, as a valve, 
to the internal orifice of the bladder. In this region, the 
mucous coat is in very close relation with the muscular coat of 
the bladder. 

The VESSELS of the bladder comprise arterial branches, derived 
from the internal iliac artery ; and its veins open into the vein 01 
the same name, after having formed an intricate plexus upon the 
sides and the base of the organ. 

The lymphatics communicate with the glands of the lumbar 
region. 

The NERVES arise from the hypogastric and sacral plex- 
uses ; from the former of which the upper portion of the organ 
is supplied, while, from the latter, the base and the neck of the 
organ are supplied. 

THE PENIS. 

The genital organ of the male sex consists of erectile tissue, 
enclosed in three compartments, called the two corpora cavernosa 
and the corpus spongiosum. Each of these compartments is 
enclosed in a sheath of its own, which is composed of fibrous 
tissue, and, by prolongations of these sheaths inwards, called tra- 
becules, each of the three compartments is subdivided into numer- 
ous minute spaces, in which are contained the blood-vessels of 
the erectile tissue of the organ. 

The two corpora cavernosa lie, side by side, upon the upper 
surface of the penis, while the corpus spongiosum lies behind the 
other two compartments, being contained in the groove between 
the corpora cavernosa. At the anterior extremity of the organ, 
this portion of the penis expands into a conical shaped mass, 
called the glans penis, which embraces and conceals the anterior 
extremity of the two corpora cavernosa, which, at this point, 
become united. 

The corpora cavernosa arise from the two tuberosities of the 



564 ORGANS OF GENERATION. 

ischium and from either of the ascending rami of that bone, and 
partly also from the descending rami of the pubes, and, after 
meeting beneath the symphysis, they pass, side by side, till they 
join, in front, to form a rounded extremity, which fits into a de- 
pression in the glans penis. The grooves, between the corpora 
cavernosa, contain the dorsal vessels and nerves, above, and the 
corpus spongiosum, below. 

The fibrous sheath, which invests the corpora cavernosa, forms 
a septum between them for the posterior two-thirds of their ex- 
tent, after they join in the median line, but is deficient in the an- 
terior third, thus affording a communication between the cav- 
ities of each. The comb-like fibres, which mark the gradual 
disappearance of this septum, form the " septum pectiniforme." 

The corpus spongiosum commences at the point of union of the 
corpora cavernosa, in a swelling called the bulb of the corpus 
spongiosum, where it is penetrated by the membranous portion 
of the urethral canal ; and passes forwards as an erectile tube, 
which encloses the urethra, till it expands into its anterior ex- 
tremity, the glans penis. 

The glans penis is the anterior extremity of that organ, and is 
protected by a prolongation of the integument of the penis, to 
which the term prepuce is applied. It presents the following por- 
tions to which special names have been applied : 
The meatus, or mouth of the urethra. 
The cervix, or constricted portion. 
The corona, or ridge of the glans. 
The framum preputii, or bridle of the prepuce. 

The integument of the penis differs from the integument of 
other localities, in being destitute of fat, in being darker colored, 
and in being more loosely connected to the adjacent parts. 

The ERECTILE TISSUE of the penis is composed of three sets 
of vessels, called, 

Afferent arteries. 
Efferent veins. 
Venous plexuses. 

The afferent arteries of the penis are chiefly derived from the 
artery of the bulb, and the artery of the corpora cavernosa ; and 
they assist in forming capillary plexuses and long tortuous arte- 
ries, called kelicine arteries. 

The efferent veins of the penis emerge from the corona gland-is, 
from the upper and lower surfaces of the corpora cavernosa, and 
from the root of the penis. Those which emerge from the three 
first situations empty into the dorsal vein of the penis, while 



THE MALE URETHRA. 565 

those which emerge from the root, empty into the prostatic 
plexus of veins and the pudic vein. 

The venous plexuses of the erectile tissue of the penis are de- 
veloped to a remarkable degree and are extremely intricate. 

THE URETHRAL CANAL. 

The urethral canal of the two sexes differs to so great a degree, 
that the female urethra will be considered in the description of 
the female genitals, and the urethra of the male sex alone will be 
here considered. 

The male urethra is about eight and a half inches in length, 
and is usually divided into three portions, called from their situa- 
tion, the prostatic, the membranous, and the spongy portion. 

The urethra is also often divided into two portions, called the 
fixed portion, which lies beneath and behind the pubic arch, and 
the pendulous portion, which is included within the spongy por- 
tion of the penis. The curve of these two portions differs ; the 
former presenting a concavity which looks upwards, and the latter 
a concavity which looks downwards. 

The former division of the urethra, however, best affords a 
clear idea of the situation, the function, and the surgical import- 
ance of the parts contained. 

The PROSTATIC PORTION comprises that part of the urethral 
canal which pierces the prostate gland. It is spindle-shaped, is 
the most dilatable and the widest portion of the urethral canal, 
and measures about one inch and a quarter in length. 

Upon its floor, may be perceived the following points of special 
interest : 

The verumontanum or caput gallinaginis. 

The prostatic sinus. 

The sinus pocularis or uterus masculinus. 

The orifices of the seminal ducts. 

The orifices of the prostatic ducts. 

The first point of interest, above mentioned, is so-called from 
its form and from a fancied resemblance to the comb of a rooster. 
It is often also called the " urethral crest." It consists of a lon- 
gitudinal ridge, three quarters of an inch in length, and is, by 
some, supposed to be the chief Seat of sensation during sexual 
intercourse. 

The prostatic sinuses are situated upon either side of the veru- 
montanum, and, into them, open the ducts of the prostate gland. 

The sinus pocularis is a small cul-de-sac, which extends into 



$66 ORGANS OF GENERATION. 

the middle lobe of the prostate, and resembles, in its shape, the 
female organ of conception. 

The seminal ducts open into the anterior part of the prostatic 
portion of the urethra. 

The MEMBRANOUS PORTION of the urethral canal is contained 
between the two layers of the triangular ligament of the perineum. 
It is so called from the character of its coats, which are almost 
entirely destitute of erectile tissue, and which are therefore ex- 
tremely thin. This portion of the urethra allows of great latitude 
of motion to the penis, and, from the absence of abundant erec- 
tile tissue, the danger of fracture of that organ, when erected, is 
therefore greatly diminished. 

The membranous portion of the urethra is shorter upon its 
lower than upon its upper surface, on account of the projection 
backwards of the bulb of the urethra, which encroaches upon its 
lower surface. 

The ducts of Cowper's glands are perceived upon the sides of 
this portion of the urethra, external to its coats, on their way to 
open into the bulb of the urethra. 

The SPONGY PORTION of the urethra comprises the remainder 
of the canal, and is contained within the corpus spongiosum. It 
is about six inches in length, and presents two enlargements, one 
at either end, called the bulb of the urethra, and the fossa navi- 
cular is. 

The bulb of the urethra is situated at the posterior part of the 
corpus spongiosum, and the fossa navicularis is situated at the an- 
terior extremity, within the glans penis. Both of these localities 
are of larger calibre than the balance of the spongy portion, and 
possess points of surgical interest, which render their anatomical 
situation important. 

The urethra has three coats, called, respectively, the muscular, 
the mucous, and the erectile coats. 

The muscular coat consists of a layer of involuntary or un- 
striped muscular fibres, which lie under the mucous coat of the 
canal. Two voluntary muscles are also connected with the urethra, 
which are not properly a portion of the muscular coat of the 
canal, but which are of physiological importance in assisting in 
the voidance of urine and the ejaculation of semen. These two 
muscles are called the compressor urethral and the accelerator 
urinae. They are usually described in connection with the anat- 
omy of the perineum. 

The mucous coat of the urethra extends throughout the entire 
length of the canal, and is covered, for the greater portion of its 



THE TESTICLE. 567 

extent, with columnar epithelium. In the fossa navicularis, how- 
ever, the epithelial covering is of the squamous variety. 

The mucous coat differs in its color in certain portions of the 
canal, being pale in the prostatic portion, and of a deeper red color 
in the two remaining portions. It is also smooth in the prostatic 
portion, and is thrown into longitudinal folds in the remaining 
portions, except when the canal is distended with urine. 

The glands of the mucous coat are called the glands of Littre, 
and are of surgical importance, since their mouths open forwards, 
and thus often afford an obstruction to the introduction of instru- 
ments into the bladder. They are most abundant in the spongy 
portion of the urethra. 

The erectile coat of the urethra is very extensively developed 
in the spongy portion, since it forms the corpus spongiosum, and 
it is also distributed as a thin layer over the membranous and 
the prostatic portions. In the latter situation, the erectile coat 
forms the caput gallinaginis. 

The urethral canal of a child is longer in its membranous por- 
tion, in proportion to the entire length of the canal, than in the 
adult, since the prostate gland is small and imperfectly developed. 
The curve of the urethra of the child is also greater than in the 
adult, since the bladder is placed higher up in the abdomen ; and 
the coats of the canal furthermore are thin and delicate, and are, 
therefore, liable to be injured in attempts at catheterism. 



THE TESTICLE. 

The testicle is the organ which secretes the seminal fluid. It is 
of oval form, and is suspended by the spermatic cord. Within 
the scrotum, it hangs obliquely, and presents an upper and lower 
extremity, two lateral surfaces, and an anterior and a posterior 
border. 

It is protected by the following external coverings : 

Integument of the scrotum. 

Dartos of the scrotum. 

Intercolumnar or external spermatic fascia. 

Cremasteric layer. 

Fascia propria or infundibuliform process. 

Tunica vaginalis, (two layers.) 
The integument of the scrotum is closely united to the dartos, 
and is divided, by the median raphe of the scrotum, into two lat- 
eral halves. 



563 ORGANS OF GENERATION. 

The dartos is the contractile layer of the scrotum, and forms 
a septum between the two testicles, called the " septum scroti." 

The external spermatic fascia is derived from the margins of 
the external abdominal ring during the descent of the testicle. 

The cremasteric layer consists of a thin covering of the 
fibres of the cremaster muscle, gathered by the testicle during its 
descent. 

The fascia propria is a covering of the testicle, which cor- 
responds to that process of the transversalis fascia, which ac- 
companies the testicle in its descent through the inguinal canal. 

The tunica vaginalis is derived from the peritoneum, and, like 
other serous membranes of the body, consists of a visceral and a 
parietal layer. It communicates, soon after the descent of the 
testicle, with the cavity of the peritoneum, but afterwards closes 
and becomes a shut sac. 

The epididymis is an appendix to the testicle, which lies on 
the posterior border, and the back part of the outer surface of that 
organ. 

Its upper extremity or head is attached to the testicle, and 
gives passage to its efferent ducts. 

Its central portion, called its body, is attached to the posterior 
border of the testicle by the tunica vaginalis. 

Its lower extremity is pointed, and is attached to the testicle 
by a dense band of fibrous tissue. 

The testicle has, in addition to its serous layer, which has 
been already mentioned, a fibrous and a vascular layer. 

The fibrous layer is called the tunica albuginea, and lies under- 
neath the serous covering of the organ. It is reflected, at the 
posterior and upper border of the organ, into the interior of the 
testicle, where it assists in supporting the vessels, nerves, and 
excretory ducts of the organ, and also, by forming trabecules, it 
divides the testicle into compartments, which contain the sub- 
stance of the gland. The vertical septum, which is formed in the 
interior of the gland by the tunica albuginea, is called the me- 
diastinum testis or the corpus HigJimorianum. 

The vascular covering is called the tunica vasculosa. The ves- 
sels, contained within this covering, penetrate into the substance 
of the gland and supply it with blood. 

The glandular structure is composed of lobules, each of which 
may be shown to consist of a few small tubules, called tubuli 
seminifcri. The length and size of these tubes has been vari- 
ously estimated, and an equal diversity exists as regards their 
number. 



THE TESTICLE. 569 

The seminal tubes, after their escape through the mediastinum 
testis, are called vasa recta, and these again, by joining with each 
other, form a collection of tubes, called the rete testis. 

The rete testis forms, in the region of the globus major of the 
epididymis, some fifteen or twenty ducts called vasa efferentia, 
which perforate the testicle and escape into the epididymis. 

The vasa effere7itia soon become convoluted and grouped into 
conical shaped bundles, called coni vasculosis which constitute the 
greater portion of the globus major. 

The coni vasculosi finally empty into the canal of the epididy- 
mis, which consists of a tube, that measures about twenty feet 
in length, and which opens into the vas deferens. This tube con- 
stitutes the true structure of the epididymis. It is usually con- 
nected with an additional tube, called the vas aberrans of Haller, 
which occasionally opens into the vas deferens, but usually ends 
in a blind extremity. 

The VAS DEFERENS is the tube, by which the semen is con- 
veyed from the epididymis to the point of origin of the ejacula- 
tory duct. Its course is as follows : 

1. Along the inner side of epididymis and the testicle. 

2. Along the back part of the spermatic cord, to the external 

abdominal ring. 

3. Through the two rings of the abdomen and the inguinal 

canal. 

4. Between the bladder and the rectum, to the inner side of 

the vesicula seminalis. 

5. Joins, at the base of prostate, with the duct of the vesicula 

seminalis, to form the ejaculatory duct. 

The vesicula seminales are two sacculated pouches, which 
act as reservoirs for semen, and which are filled by a regurgitant 
current from the vas deferens of either side. They are about 
two and a half inches in length, and are situated between the 
bladder and the second portion of the rectum. They consist of 
a tube, coiled upon itself, which measures about six inches in 
length. 

The ejaculatory ducts are formed, by the junction of the ducts 
of the vesiculae seminales and the vasa deferentia, upon either side 
of the body. They are about three-quarters of an inch in length, 
and they terminate at the anterior extremity of the prostatic por- 
tion of the urethra, upon either side of the verumontanum. 



570 



THE PROSTA TE GLAND. 



THE PROSTATE GLAND. 



The prostate gland encircles the neck of the bladder of the 
male, and measures one and one-quarter to one and one-half 
inches in its antero-posterior diameter, one and three-quarter 
inches in its greatest transverse diameter, and about three-quar- 
ters of an inch in depth. It is of a pale color, and consists, to a 
great extent, of involuntary muscular tissue, the glandular portion 
being decidedly subordinate to the muscular element. Its ducts 
open into the prostatic portion of the urethra, and its secretion 
serves to dilute the semen. 

This gland consists of two lateral lobes of large size, and, in 
the deep notch between them at its posterior part, of a small tri- 
angular mass, to which the name " middle lobe of the prostate " 
is applied. 

The size of the prostate gland, especially of its middle lobe, 
varies ; since, as life advances, the gland tends to increase in 
size, on account of hypertrophy of its structures. 

The prostate gland is enveloped in a fibrous capsule, which is 
derived from the pelvic and the deep perineal fasciae. 

The arteries, which are distributed to this gland, are derived 
from the internal pudic, the vesical arteries, and the middle hem- 
orrhoidal artery. The veins form large plexuses at the sides 
and the base of the gland, and empty into the internal iliac vein. 

The nerves are derived from the hypogastric plexus of the 
sympathetic system. 

The various points of interest, contained within the internal 
cavity of the gland, have already been described as pertaining to 
the prostatic portion of the urethral canal. 

The prostate gland lies in close relation with the rectum. An 
invaluable means of diagnosis, in case of disease of this gland, is 
thus afforded by rectal touch. The posterior edge of this gland 
is used as a guide, in puncture of the bladder through the 
rectum. 



THE SPERMATIC CORD. $71 



THE SPERMATIC CORD. 

The spermatic cord extends from the globus minor of the epi- 
didymis to the internal abdominal ring. It is about four inches in 
length, and is composed of the following structures : 

1. The vas deferens. 

2. Spermatic artery. 

3. Cremasteric artery. 

4. Artery of the vas deferens. 

5. Spermatic veins. 

6. Spermatic plexus of nerves. 

7. A branch of the ilio-inguinal nerve. 

8. A branch of the genito-crural nerve. 

9. Vas aberrans of Haller. 

10. Coverings. 

11. Lymphatics. 

Of these various structures, the vas deferens lies at the pos- 
terior portion of the cord, while the veins form a plexus both in 
and upon it, and are sometimes called the pampiniform plexus. 

The vas aberrans of Haller is a narrow and tortuous tube, 
which arises either from the vas deferens or from the canal of the 
epididymis. It passes upwards in the spermatic cord, where it 
usually ends in a blind extremity. It varies in its length from 
two to fourteen inches. 

The coverings of the spermatic cord differ in the various parts 
of its course. Two coverings, viz., the fascia propria of the tes- 
ticle and spermatic cord, and the cremasteric fascia, invest it for the 
greater portion of its length ; while, below the external abdominal 
ring, the tunica vaginalis, the inter columnar fascia, the dartos, and 
the integument also protect and partially cover it. 

All the parts, which enter into the formation of the spermatic 
cord, are bound together by a delicate areolar tissue. 



572 ORGANS OF GENERATION. 



GENITAL ORGANS OF THE FEMALE. 

The external genitals of the female comprise the following 
parts, which are specially named : 

1. The mons veneris. 

2. The labia majora. 

3. The labia minora or nymphae. 

4. The clitoris. 

5. The meatus urinarius. 

6. The vestibule. 

7. The hymen. 

8. The aperture of the vagina. 

The mons veneris is a collection of fat, in front of the pubes. 
It is covered with hair after puberty, and it forms a rounded 
eminence, which serves as a protection against injury to the 
deeper parts, during coition or in case of accidental violence. 

The labia majora are the two anterior and the thickest lips of 
the vulva. They form, by their points of junction, the anterior and 
the posterior commissures of the vulva. They are covered exter- 
nally by integument and mucous membrane, and they contain, in 
their interior, areolar and dartoid tissues. 

The nymphce&vQ two small folds which are attached above, thus 
forming a preputial covering for the clitoris, and which are lost, 
below, upon the sides of the labia majora. 

The clitoris is the analogous organ to the penis in the male 
sex. It differs from that organ, however, in being S7naller in size 
and imperforate, and in possessing no corpus spongiosum. It has 
analogous muscles, and possesses a suspensory ligament, two 
crura, a glans, a body, and a prepuce. 

The meatus urinarius is situated upon the upper wall of the 
vagina, at a point about one inch below the clitoris. 

The vestibule is a triangular space, at the upper and anterior 
part of the vulva, which is bounded, upon either side, by the 
nymphae, and, behind, by the meatus urinarius. 

The hymen is a fold of mucous membrane, which varies greatly 
in its form and its extent. It may be a complete septum, which en- 
closes the entire outlet of the vagina, or a perforated septum, 
with one central orifice or numerous smaller openings, or, finally, 
a semilunar fold with a free concave border. In some cases, the 
hymen is absent, and, in others, the remnants only of a previous 
hymen exist, in the form of small irregular eminences, called ca- 
runculce myrtiformes. 



THE VAGINA. 573 

The aperture of the vagina is surrounded by the sphincter 
vaginae muscle, and, in the virgin, is often closed by the hymen. 
The internal organs of generation of the female comprise, 

1. The vagina. 

2. The uterus. 

3. The appendages to the uterus. 

The VAGINA is a musculo-erectile tube, which serves to estab- 
lish a communication between the cavity of the uterus and the 
external world. It is curved to accommodate itself to the axis 
of the pelvic cavity, and measures about four inches in length, 
upon its anterior wall, and from five to six inches, upon its pos- 
terior wall. 

The anterior wall of the vagina is in relation with the urethra 
and the base of the bladder ; the posterior wall is in relation with 
the rectum, in its lower three-fourths, and, in its upper fourth, it 
is covered by peritoneum ; while its lateral walls are in relation 
with the broad ligaments of the uterus, the levator ani muscle, 
and the pelvic fascia. 

The coats of the vagina are three in number, and are called., 
from within outwards, the mucous, the erectile, and the muscular 
coats. 

Near to the aperture of the vagina, may be perceived two 
points of anatomical interest, called the bulbs of the vestibule, and 
the glands of Bartholine. 

The bulbs of the vestibule consist of two distinct plexuses of 
veins intermixed with erectile tissue, which are supposed to be 
analogous to the two halves of the bulb of the male urethra. 

The glands of Bartholine are situated upon either side of the 
vaginal aperture, and are analogous to the glands of Cowper, in 
the male sex. 

The vagina serves the three-fold purpose, of a channel for the 
escape of menstrual blood, a means of exit for the child in parturi- 
tion, and a means of entrance for the seminal fluid to the cavity 
of the uterus. 

The FEMALE URETHRA, although not properly one of the 
organs of the genital apparatus, differs markedly from that of the 
male, and is best considered in connection with the vagina, since 
it is contained between its coats. 

This canal is about one and a half inches long, and possesses 
a very high degree of dilatability. It passes between the coats 
of the anterior wall of the vagina, and opens at the posterior part 
of the vestibule. It pierces, like the urethra of the male sex. the 
triangular ligament of the female perineum, and is surrounded 



574 ORGAN OF GENERATION. 

also by the compressor urethrae muscle. Its coats consist of a 
mucous, an erectile, and a muscular coat. 



THE UTERUS. 

The organ of conception is pear-shaped, and is flattened from 
before backwards. It is situated between the bladder and the 
rectum, and its neck protrudes into the cavity of the vagina. 
It is retained in its position, principally, by the broad and the 
round ligaments of the organ. 

The uterus presents for examination the following parts, which 
possess special interest : 

i. A fundus. 

2. A body. 

3. A cervix or neck. 

4. A cavity. 

5. Eight ligaments. 

6. Three coats (a serous, a muscular, a mucous). 

7. Vessels and nerves. 

8. Appendages. 

The fundus of the organ is that portion which is directed up- 
wards. It is broad and covered with peritoneum. 

The body of the organ is adherent to the bladder in front, at 
its lower part, and is covered by peritoneum, at the upper part ; 
behind, it is covered by peritoneum and is in close relation with 
the small intestine ; while, at the sides, the Fallopian tubes, the 
round ligaments, and the ovarian ligaments are attached to it. 

The neck of the organ affords attachment for the upper end 
of the vagina. It measures, in length, nearly the same as does 
the body of the organ, viz., about one and a half inches. 

The cavity of the uterus is divided into two portions, called 
the cavities of the body, and of the cervix. 

The cavity of the body is triangular, and communicates with 
the two Fallopian tubes. The mucous lining of this cavity pre- 
sents peculiarities, which will be considered when the mucous 
membrane of the organ is described. 

The cavity of the cervix is fusiform, and measures about one 
inch and a quarter in length. The point of junction of the 
two cavities is called the os internum, while the lower opening 
of the cavity of the cervix is called the os externum. 

The ligaments of the uterus are eight in number, and may 
be divided into two sets as follows: 



THE UTERUS. 575 

True ligaments. Formed by the peritoneum. 

Two round ligaments. Two broad ligaments. 

Two anterior ligaments. 
Two posterior ligaments. - 

The anterior ligaments connect it with the bladder 

The. posterior ligaments connect it with the rectum. 

The broad ligaments extend from the sides of the organ to the 
sides of the pelvis, and form three folds, which enclose, respec- 
tively, the ovaries, the Fallopian tubes, and the round ligaments, 
in their order from behind forwards. 

The round ligaments arise at the superior angle of that organ, 
and, after passing in the anterior fold of the broad ligament of 
either side, enter the inguinal canals and terminate in the labia 
majora. The tubular process of the peritoneum, which accom- 
panies this ligament, in the inguinal canal, is called the canal of 
Nuck ; but it seldom exists, as a distinct canal, except in the 
foetus. 
Coats. 

The muscular coats of the uterus are three in number and are 
called respectively, the outer, the middle, and the inner layers. 

The outer layer is the thinnest stratum of the three, and is ar- 
ranged as transverse fibres, which extend upon the various liga- 
ments of the uterus, after they reach the borders of that organ. 

The middle layer is a thick stratum, and consists of fibres which 
run in every direction. 

The inner layer is arranged as two cones, whose apices cor- 
respond to the orifices of the Fallopian tubes, and which become 
united in the median line of the uterus. The direction of its 
fibres varies, therefore, with the portion of the uterus which is ex- 
amined, being circular, in some localities, and transverse in other 
situations. 

The serous coat covers the anterior surface, for its upper 
three-fourths, the fundus, and the whole of the posterior sur- 
face of the organ. 

The mucous coat differs in its appearance in the body and in 
the cervix of the organ, as follows : 



In the Body. 
Is smooth. 
Is thin. 

Is firmly adherent to the uterus. 
Has ciliated epithelium upon it. 
Has utricular follicles. 
Has a thin secretion. 



In the Cervix. 
Is thrown into rugae. 
Is thick. 

Is loosely attached. 
Has squamous epithelium. 
Has glands of Naboth. 
lias a thick and viscid secretion. 



576 ORGANS OF GENERATION. 

The VESSELS comprise branches of the uterine and the ova- 
rian arteries, the accompanying veins, and the lymphatic vessels 
of the fundus and of the cervix. 

The NERVES are derived from the inferior hypogastric and the 
ovarian plexuses, and from the third and fourth sacral nerves. 

The APPENDAGES to the uterus comprise the following struct- 
ures: 

The Fallopian tubes 
The ovaries. 

The ligament of the ovary. 
The organ of Rosenmiiller. 

The Fallopian tubes commence at the upper extremities of the 
cavity of the body of the uterus, where they each present a small 
opening, called the internal opening of the tube, and extend 
outwards, in the middle fold of the broad ligament of the uterus, 
to expand into a trumpet-shaped extremity, called the fimbriated 
extremity of the tube, since it is surrounded by a fringe-like series 
of processes, the fimbriae, which connect the outer extremity of 
the tube to the ovary. This tube is perforated by a canal which 
transmits the ovum, during the period of menstruation. The 
Fallopian tube is composed of three coats, the serous, the mus- 
cular, and the mucous coats. 

The serous coat is composed of a reflection of the peri- 
toneum. 

The muscular coat is formed by a continuation of the longi- 
tudinal and the circular fibres of the uterus. 

The mucous coat is lined with ciliated epithelium, and is con- 
tinuous, externally, with the peritoneum. 

The OVARIES are two oval bodies, which lie in the posterior 
fold of the broad ligament, below the external extremities of the 
Fallopian tubes. They are composed of a serous coat, a fibrous 
coat, called the tunica albuginea, and a stroma. 

The serous covering invests the entire structure, except at 
its anterior margin, where the hilum of the organ may be 
perceived. 

The tunica albuginea differs, in no way, from the fibrous coat 
of all those organs, where this covering is firm and dense. 

The stroma or the true substance of the ovary is principally 
composed of small sacs, called Graafian vesicles or ovisacs, in a 
condition of more or less perfect development. 

Each of these vesicles may vary, in point of size, from one- 
eightieth to one-sixth of an inch in diameter, according to its 



THE OVARY. 577 

state of development, and, when perfectly formed and matured, 
presents the following component parts. 

An external fibro-vascular covering. 

An internal coat, called the ovi-capsule. 

A layer of nucleated cells, called the membrana 

granulosa. 
An albuminous fluid. 

The ovum, surrounded by the pro tiger -us disc. 
The matured Graafian vesicles are found near to the surface 
of the ovary, forming small projections upon it. 

The ovum, in all perfectly matured vesicles, measures about 
one hundred and twentieth of an inch in diameter, and presents 
the following component parts. 

The vitelline membrane or zona pellucida. 
The yolk or vitellus. 
The germinal vesicle. 
The germinal spot. 
The rupture of a Graafian vesicle is always associated with the 
development of a spot within the ovary, which exhibits an abnor- 
mal appearance and arrangement, and which is called the corpus 
luteum. In case of impregnation of the discharged ovum, the 
corpus luteum continues to develop, and, for that reason, two 
kinds of corpora lutea are recognized, viz., the true, when impreg- 
nation has occurred, and the false, when impregnation has not 
occurred. 

The artery of the ovary is derived from the internal iliac artery 
and enters at the hilum of the organ. The ovarian vein escapes 
at the same situation and opens into the inferior vena cava, on the 
right side, and, on the left side, into the left renal vein. 

The nervous supply is derived from the ovarian plexus of the 
sympathetic. 

The organ of Rosenmiiller or parovarium, consists of a group 
of scattered tubules, situated between the layers of the broad liga- 
ment and between the ovary and the Fallopian tube. 

These tubules are lined with epithelium, but have no external 
opening. They converge, however, to one large duct, which 
ramifies in the broad ligament, and which is called the duct of 
Gcertner. 



578 ORGAN OF SIGHT. 



THE EYE. 

The organ of vision is situated within the cavity of the orbit, 
and is there retained by its muscles, by the optic nerve, and by 
areolar tissue and the conjunctival attachments. 

The eye may be described as consisting of three coats, and 
three refracting media, namely : 

Coats of the eye. Refracting media. 

Sclerotic coat and the cornea. Aqueous humor of the eye. 
Choroid coat and the iris. The lens and its capsule. 

The retina. The vitreous humor and its 

hyaloid membrane. 

The SCLEROTIC COAT of the eye consists of a strong fibrous 
membrane, which covers the posterior five-sixths of the entire 
globe of the eye, and which is continuous, in front, with the 
cornea. 

Its outer surface is white in color and affords attachment to 
the muscles of the eye-ball. It is covered by the ocular reflection 
of the conjunctiva, 

Its inner surface is brown in color and is in close relation with 
the choroid coat, to which it is attached by a cellular membrane, 
called the lamina fusca. It is also grooved for the transmis- 
sion of the ciliary vessels and nerves. To this surface of the 
sclerotic coat of the eye, is attached the ciliary muscle, at its an- 
terior portion ; and a circular groove may be perceived in this 
region, which marks the outer wall of the canal around the cir- 
cumference of the iris, the canal of Schlemnt. 

At the posterior portion of the eye-ball, the sclerotic coat is 
pierced by the optic nerve and is continuous with the sheath 
of that nerve. It is also perforated, at about this point, by the 
arteria centralis retinae, and by numerous nerve filaments. The 
term lamina cribrosa is applied to this portion, on account of its 
numerous openings. 

The CORNEA is the covering of the anterior sixth of the eye- 
ball and is continuous with the sclerotic coat, from which it differs 
however, in its transparency, its structure, and its curve. Its cir- 
cumference is nearly circular in its outline, and it is more promi- 
nent than the rest of the eye-ball, since its curve forms an arc of 
a smaller circle. The degree of its curvature varies greatly, how- 
ever, both in individuals, and as age advances. 

The cornea has been found to consist of the following struc- 
tures : 



STRUCTURE OF THE EYE. 579 

The anterior epithelial coating (two or three layers). 

The anterior elastic layer. 

The body of the cornea, (fifty or sixty layers of cells). 

The posterior elastic layer. 

The posterior epithelial coating, (one layer). 

The CHOROID coat of the eye is a vascular and pigmentary 
layer, which is continuous, in front, with the iris, the ciliary pro- 
cesses, the ciliary muscle, and the ligamentum pectinatum. 

This layer possesses a dark brown color, is thickest at its pos- 
terior portion, lies between the sclerotic and the retina, and allows 
of the passage of the vessels, which are distributed to the anterior 
portions of the eye. It is pierced by the optic nerve, at its pos- 
terior portion ; and, on its outer surface, it is grooved for the 
vessels which it transmits, while, on its inner surface it is smooth 
and lies in contact with the retina. 

The choroid coat may be described as consisting of three dis- 
tinct layers, namely : 

The external or venous layer (layer of venae vorticosae). 
The middle or capillary layer (tunica Ruyschiana). 
The internal or pigmentary layer. 

The choroid coat of the eye is prolonged, in the anterior part 
of that organ, into a curtain-like expansion behind the iris, to 
which the name " ciliary processes'* is applied, since it presents 
numerous folds. These processes are similar in their structure 
to the choroid, but are less vascular. They are attached to the 
suspensory ligament of the lens, and to the adjacent portion of 
the retina. 

The IRIS is a perforated curtain, which prevents the entrance 
of light into the chamber of the eye, except through the opening 
within it, which is called the pupil. It is continuous, at its free 
edge, with the ciliary muscle, the ciliary processes, the choroid 
coat, and, by means of the ligamentum pectinatum, with the 
cornea and the sclerotic coat of the eye. A canal extends around 
the circumference of its attached border, which is called the sinus 
circular is iridis or the canal of Scklemm. 

The posterior surface of the iris is purple in color, and is called, 
from its resemblance to the inside portion of a grape skin, the uvea. 

The anterior surface of the iris varies in its color in different 
individuals, and is marked by wavy lines which converge. 

The iris is composed of a stroma formed by two sots o( mus- 
cular fibres, the circular and the radiating set ; and, in addition, 
some pigment cells, which give color to the pupil. 



5 SO ORGAN OF SIGHT. 

The arteries of the iris are derived from the long ciliary arte- 
ries, and from those of the ciliary processes. 

The nerves of the iris are derived from the ciliary nerves, which 
are intimately associated with the 3d pair of cranial nerves, at 
the ciliary ganglion of the orbit. It is through this nerve, that 
the reflex act of contraction of the pupil is performed, when the 
optic nerve is oppressed by an excessive amount of light within 
the chamber of the eye. 

The RETINA is the nervous layer of the eye, by which the spe- 
cial sense of vision is afforded. During life, the retina is translu- 
cent and of a pinkish color, but, after death, it becomes opaque 
and whitish in appearance. 

The retina lines the posterior four-fifths of the eye, and is 
carried forwards to the base of the iris. Its external surface lies 
upon the choroid coat, which affords for it a dark background, 
while its internal surface lies in contact with the hyaloid mem- 
brane of the vitreous humor. Its anterior margin is called the 
ora serrata, from its ragged outline. 

Upon the posterior portion of the retina may be perceived the 
following points of interest : 

The colliciilns, where the optic nerve escapes. 
The yellow spot (macula lutea, limbus luteus of Sommering). 
The fovea centralis, in the centre of the yellow spot. 
The orifice of escape of the arteria centralis retinae. 
The structure of the retina, although still a subject of investi- 
gation, presents the following points of practical anatomical im- 
portance. 

The pigmentary layer. 

The layer of Jacob's rods and cones. 

The layer of granules, or the middle layer. 

The layer of expanded nerve fibres and of nerve cells. 

The membrana limitans. 

The rods and the cones, which form the characteristic feature 
of the external layer, are arranged perpendicularly, and the bulb- 
ous ends of the cones are directed towards the internal surface of 
the retina. No rods are present in the macula lutea. 

The granules of the middle layer vary in their size and appear- 
ance, and this layer is therefore, by some, subdivided into from 
three to five layers. These layers are traversed by fibres, called 
sustentacular fibres or the fibres of Midler. 

The nervous layer is the most internal, except the membrana 
limitans, and the nerve cells, contained within it, communicate 



STRUCTURE OF THE EYE. • 58 I 

with the expanded fibres of the optic nerve. It is often divided 
into two layers, called the ganglionic, and the nervous layer. 

The arteries of the retina are derived from the arteria centralis 
retinae, which pierces the optic nerve before it enters the eye. 

The AQUEOUS HUMOR of the eye is contained within a space 
between the anterior surface of the lens of the eye and the pos- 
terior surface of the cornea. This space contains also the iris, 
which floats in the aqueous humor, and, by some anatomists, the 
cavity of the aqueous humor is divided, by it, into an anterior and 
a posterior aqueous chamber. The aqueous humor differs slightly 
from water, as it contains chloride of sodium and a trace of other 
solid matters. 

The LENS of the eye is a double convex, transparent body, 
whose convexity is most marked at its posterior surface. It is en- 
closed in a capsule of its own, and is held in position by a suspen- 
sory ligament. It is situated between the iris and the vitreous 
humor, and its circumference is surrounded by a canal, called the 
canal of Petit. 

The structure of the lens consist of superimposed layers which 
are parallel with the surfaces of the lens, and each of these layers 
may be also subdivided into three segments, which are of nearly 
equal size. 

The capsule of the lens is very elastic and brittle in its nature, 
and, when ruptured, it tends to curl up spontaneously. It 
affords attachment to the suspensory ligament of the lens, and is 
attached, behind, to the hyaloid membrane. It is separated from 
"the anterior surface of the lens, by a layer of cells, which, after 
death, absorb moisture and break down into a fluid, called the 
liquor Morgagni. 

The suspensory ligament of the lens is sometimes called the 
zonula of Zinn. It is attached to the capsule of the lens and is 
separated from the hyaloid membrane by the canal of Petit. Its 
anterior surface is thrown into small radiating folds, called the 
processus zonulce, which are received between the ciliary pro- 
cesses. 

The VITREOUS HUMOR is contained within the posterior cham- 
ber of the eye, between the posterior surface of the lens and the 
retina. It is enclosed in a capsule, called the hyaloid membrane \ 
and it is excavated, in its anterior portion, for the reception of 
the lens. 

The hyaloid membrane is closely attached to the posterior sur- 
face of the capsule of the lens, and forms the posterior boundary 
of the canal of Petit. 



582 ORGAN OF SIGHT. 

The vitreous humor is a thick albuminous fluid, which, in the 
foetus, is characterized by a reticulated structure within its sub- 
stance; but in the adult, it is destitute of any internal struc- 
ture. 

The ciliary muscle of the eye is a ring of involuntary muscular 
tissue, which is situated at the anterior part of the choroid coat 
and upon the outer side of the ciliary processes. It is of great 
physiological importance, since it serves to adjust the vision to 
distances, by altering the shape of the lens of the eye by the 
pressure which it exerts upon it. 

The ligamentum pectinatum is a fibrous band, which unites the 
middle and outer coats of the eye, although it is also connected 
with the posterior elastic layer of the cornea and the iris, into the 
latter of which it gives off fibres, from whose appearance the lig- 
ament receives its name. 



APPENDAGES TO THE EYE AND LACHRYMAL 
APPARATUS. 

The eye has the following appendages, which demand a sepa- 
rate description. 

The eyebrows. 
The eyelids. 
The conjunctiva. 
The eyebrows consist of a thickened fold of integument, which 
is covered with hair and which corresponds to the upper edge of 
the orbital cavity. 

The eyelids are two movable folds, which afford a protective 
covering to the eyeball and which are joined at either extremity, 
where their angles of junction are called the external and the in- 
ternal canthus. 

The external angle of the eyelids is higher than the internal 
angle, as a rule, and the size of the fissure between the eyelids 
gives the appearance of increased size to the eyes, which is often 
mistaken for an actual rather than an apparent increase of de- 
velopment. 

The inner canthus of the eye presents the following points 
which have been specially named : 

The lacus lachrymalis. 
The caruncula lachrymalis. 
The plica semilunaris. 
The lacus lachrymalis is a triangular space, in which is per- 
ceived the caruncula lachrymalis ; and the plica se7nilunaris 



APPENDAGES TO THE EYE. 583 

is a fold of mucous membrane, which often encloses a piece of 
cartilage. 

The upper eyelid is the largest of the two lids, and is the most 
movable, since it connected to the levator palpebrae muscle. 

When the eye is shut, the eyeball is moved upwards and in- 
wards so that the cornea is covered by the upper lid. This is 
explained as a measure on the part of Nature to protect the cor- 
nea from dirt and also to prevent the entrance of light into the 
eye in case of separation of the eyelids. 

The lower lid, when in the act of closing, is not only raised, 
but is also drawn inwards for a distance of about one-twelfth of 
an inch, by which movement all particles of dust remaining, as well 
as any excessive moisture, is swept towards the inner canthus. 

The EYELIDS are composed of the following parts, which are 
specially named : 

Integument. 

Subcutaneous areolar tissue. 

Fibres of the orbicularis muscle. 

The tarsal cartilages. 

Tarsal ligaments. 

The tendo oculi. 

The tensor tarsi muscle. 

The levator palpebrae muscle (in upper lid). 

Palpebral conjunctiva. 

Meibomian glands. 

Eyelashes. 

The conjunctiva is usually divided into two portions, called the 
palpebral and the ocular portions. The palpebral portion is the 
thickest, the most opaque, and the most vascular. The ocular 
portion is often divided into the corneal and the sclerotic portions, 
since they differ somewhat in their construction. 

The LACHRYMAL APPARATUS comprises the lachrymal gland, 
the lachrymal canals, the lachrymal sac, and the nasal duct. 

The lachrymal gland \s situated in a depression in the roof of 
the orbit, and is about the size of an almond. It gives off six or 
eight ducts, which empty into the upper fold of the conjunctiva. 

The lachrymal canals commence at minute orifices, upon the 
margin of the lids, called the puncta lachrymalia^ and pass in a 
curved direction, at either border of the lacus lachrymalis, till 
they terminate in the lachrymal sac, which receives the tens as 
they escape. 

The lachrymal sac is the upper and the dilated portion of the 



584 ORGAN OF SIGHT. 

nasal duct. It lies in the lachrymal groove and is crossed, in 
front, by the tendo oculi, and behind, by the tensor tarsi muscle. 

The lower punctum lachrymalis is larger and more external 
than the upper, and the mouths of both are directed backwards so 
as to afford the most easy and direct access for the tears. In 
facial paralysis, cicatrices, or other conditions which tend to alter 
the direction of the mouths of these ducts, the tears no longer 
are assisted to flow in their proper channels, and they escape over 
the cheek. 

The tendo oculi> to which the cartilages and the muscles of the 
eyelids are attached, lies over the lachrymal sac, and, by being 
made tense during the shutting of the eyelids, is supposed to 
create alternating pressure upon the sac and thus to act as a pump 
to draw the tears into the nasal duct. 

The nasal duct is a membranous canal, three-quarters of an inch 
in length, and is contained within the osseous canal, formed by 
the superior maxillary, the lachrymal, and the inferior turbinated 
bones. Its lower orifice is partially closed by a fold of the mucous 
membrane of the nasal cavity. This canal is narrowest at its 
middle portion. Its lower opening is within the inferior meatus 
of the nasal cavity, and is situated about one-quarter of an inch 
behind the bony edge of the nose. 

THE EAR. 

The organ of hearing is composed of the following divisions. 

1. The external ear. 

2. The middle ear or tympanum. 

3. The internal ear or labyrinth. 

External ear. 

The external ear consists of two distinct portions called the 
pinna or auricle, and the external auditory canal. 

The PINNA is composed of cartilage, and forms that projec- 
ting portion which assists in directing sound into the external 
auditory canal. Its surface is irregular in form, and certain names 
are applied to the various depressions and elevations upon it. 

The concha is the central depression which leads to the audi- 
tory canal. 

The tragus is a conical projection on its under surface, which 
is usually covered with a few hairs. 

The anti-tragus is an eminence of smaller size, situated behind 
the tragus, and separated from it by a deep notch called the in- 
cisura antitragica. 



THE EXTERNAL EAR. 585 

The helix is the external curved margin of the cartilage of the 
ear. 

The fossa of the helix is the groove which lies underneath the 
helix, throughout nearly its whole extent. 

The antihelix is a prominence upon the cartilage of the ear 
which lies nearly parallel with the helix. It forms the posterior 
boundary of the central depression or concha, and, at its upper 
portion, it bifurcates to form a depression called the fossa. 

The fossa of the antihelix is bounded by the bifurcation of the 
antihelix, and also in front by the helix. 

The lobule of the ear is the soft pendulous portion, which hangs 
from the lower part of the cartilage of the ear. 

The cartilage which composes the pinna is not an entire struc- 
ture, but is deficient in some places, where it is joined together 
by ligaments. The cartilage, as a whole, is also united to the 
skull by certain ligaments, which are called the extrinsic ligaments 
of the pinna, in contra-distinction to the ligaments which connect 
the separate parts of the cartilage, which are called the intrinsic 
ligaments of the pinna. 

The muscles of the pinna are also divided into an intrinsic and 
an extrinsic set, since some act upon only parts of the cartilage, 
while others act upon the whole pinna. 

The integument which covers the cartilage of the pinna is very 
closely adherent and is richly supplied with sebaceous glands, es- 
pecially in the regions of the concha and the fossa of the helix. 
It is also supplied with vessels and nerves. 

The EXTERNAL AUDITORY CANAL is that portion of the exter- 
nal ear, which extends from the concha inwards to the membrana 
tympani of the ear. It is one and a quarter inches in length, and 
is directed differently in different portions of its course. If the 
pinna be drawn upwards and backwards, however, the canal will 
be rendered more nearly straight. Its floor is longer than its 
roof on account of the obliquity of the membrana tympani. 

This canal is usually divided into a cartilaginous and a bony 
portion, the former of which is a continuation of the pinna, and 
the latter is comprised within the temporal bone. 

The cartilaginous portion is about one-half of an inch in length, 
and is firmly attached to the circumference of the external auditory 
meatus in the temporal bone. At the upper and back part ot the 
canal, the cartilage is absent and is replaced by fibrous tissue. 

The osseous portion is about three-quarters o( an inch in 
length, and, at its outer extremity, is expanded into a rough 
margin for the attachment of the pinna. 



586 ORGAN OF HEARING. 

The integument of this canal is thin and closely adherent to 
the cartilaginous portion. It contains hair follicles and sebaceous 
glands, near its external opening, and numerous ceruminous 
glands throughout its entire length. 

Middle ear or tympanum. 

The cavity of the middle ear is situated between the external 
auditory canal and the labyrinth of the ear, from side to side ; be- 
tween the carotid canal and the mastoid cells, from before back- 
wards ; and between the anterior surface of the petrous portion 
of the temporal bone and the jugular fossa, from above down- 
wards. It presents for examination the following parts : 

An outer wall. 
An inner wall. 
A posterior wall. 
An anterior wall. 
A floor. 
A roof. 

The OUTER WALL is formed by the membrana tympani, and 
by the small portion of bone surrounding it. It presents two open- 
ings for the chorda tympani nerve, called the iter chordce posterius 
and the iter chordce anterius or the canal of Huguier, and a fissure 
called the fissure of Glaser. Through this latter opening, pro- 
trudes the long process of the malleus, and, through it, enters 
also the tympanic branch of the internal maxillary artery, and, 
according to some authorities, the tendon of the laxator tympani 
muscle, while by others the existence of such a muscle is denied. 

The INNER WALL presents the following points of interest, to 
which special names have been applied : 

1. The promontory, which is a large rounded eminence formed 

by the first turn of the cochlea. Its surface is grooved 
for the filaments of Jacobson's nerve. 

2. The fenestra ovalis, which is an opening into the vesti- 

bule, and which is closed by the stapes and its annular 
ligament. 

3. The feyiestra rotimda, which is an opening into the scala 

tympani, and which is closed by the internal membrane 
of the tympanum {membrana tympani secondaria) 

4. The pyramid, which is the enclosing cavity of the sta- 

pedius muscle, and, at the apex of which, the orifice, 
through which the tendon of that muscle escapes, may 
be perceived. 



THE TYMPANUM. 587 

5. The ridge of bone, which indicates the course of the aquae - 
ductus Fallopii, as it passes backwards and downwards. 

The POSTERIOR WALL presents the openings of the mastoid 
cells, which are contained within the mastoid process of the tem- 
poral bone. 

The ANTERIOR WALL presents four points of special interest 
as follows : 

1. The internal opening of the Eustachian tube, which is 

situated near to the floor of the cavity. 

2. The opening for the tensor tympani muscle, which is situated 

near to the roof of the cavity. 

3. The a7iterior pyramid, which is a prominence of bone sur- 

rounding the opening for the tensor tympani muscle. 

4. The processus cochlea for mis ^ which is a thin plate of bone 

between the openings of the Eustachian tube and the 
canal of the tensor tympani muscle. 
The FLOOR corresponds to the jugular fossa of the petrous 
portion of the temporal bone, and lies directly above it. It pre- 
sents a small opening, through which Jacobson's nerve enters the 
tympanum. 

The ROOF is separated from the cranial cavity by a thin plate 
of bone, and corresponds to a depression on the anterior surface 
of the petrous portion of the temporal bone. 

Bones of the Tympanum. 

The tympanum has, within its cavity, three small bones, 
which serve to connect the membrana tympani with the annular 
ligament which covers the opening of the fenestra ovalis, and thus 
to allow of the transmission of the sound impulse to the scala 
vestibuli of the internal ear or labyrinth. These three bones are 
called the malleus, the incus, and the stapes. 

The MALLEUS, so called from its resemblance to a hammer, 
is the most external bone and is connected to the membrana 
tympani by a process called the manubrium, which is inserted 
between the mucous and the fibrous coats of that membrane. It 
presents the following points of interest : 

A head. 

A neck. 

The manubrium. 

A processus gracilis. 

A processus brevis. 
The head articulates with the incus, and is connected to the 
roof of the tympanum by a suspensory ligament. 



588 'ORGAN OF HEARING. 

The neck affords attachment to the laxator tympani mus- 
cle. 

The manubrium or handle of the malleus is inserted into a 
space between the mucous and fibrous layers of the membrana 
tympani. 

The processus gracilis is an extremely long and delicate pro- 
jection, which extends forwards and outwards into the fissure of 
Glaser. 

The processus brevis of the bone projects, from the root of the 
manubrium, outwards towards the upper portion of the membrana 
tympani, and affords attachment to the tensor tympani muscle. 

The INCUS, so-called from its resemblance to an anvil, although 
it is perhaps more like a bicuspid tooth with its roots widely sep- 
arated, is the central bone of the cavity of the tympanum and 
articulates with the malleus and the stapes. It presents the fol- 
lowing points of interest : 

A body. 
A long process. 
The os orbiculare. 
A short process. 

The body articulates with the malleus, and is connected to the 
roof of the tympanum by a suspensory ligament. 

The long process lies nearly parallel with the manubrium of 
the malleus, and terminates in nodule of bone termed the " os 
orbiculare." 

The os orbiculare is sometimes described as the fourth bone of 
the tympanum, since it is separate from the incus in the foetus. 
It articulates with the head of the stapes. 

The short process is attached to the posterior wall of the tym- 
panum by the posterior ligament. 

The STAPES is the most internal bone of the tympanum and 
is so-called from its resemblance to a stirrup. It articulates with 
the os orbiculare of the incus, and is attached to the annular lig- 
ament around the edge of the fenestra ovalis. It presents the 
following points of interest : 

A head. 
A neck. 
Two crura. 
A base. 

The head articulates with the long process of the incus 
through the os orbiculare. 

The neck is the constricted portion below the head. It 
affords attachment to the stapedius muscle. 



MUSCLES OF TYMPANUM. $%g 

The two crura serve to connect the neck of the bone with 
the base. 

The base is broad, and is connected to the annular ligament 
around the margin of the fenestra ovalis. It thus conveys the 
sound impulse to the labyrinth. 

The MUSCLES of the tympanum are three in number, and may 
be described as follows : 

The tensor tympani. 
The laxator tympani. 
The stapedius. 

Tensor Tympani. 

Origin. 

From the under surface of the petrous portion of 
the temporal bone, and from the cartilaginous portion 
of the Eustachian tube. 
Insertion. 

Into the manubrium and the processus brevis of the 
malleus, near to the root of that process. 

Laxator Tympani. 

(The existence of muscular fibres is denied by some authori- 
ties, and it is probably a fibrous cord only.) 
O right. 

From the spine of the sphenoid bone, and the Eus- 
tachian tube. 
Insertion. 

Into the processus gracilis of the malleus, and occa- 
sionally into the neck of that bone. 

Stapedius. 

Origin. 

From the interior of the pyramid, on the inner wall 
of the tympanum. 
Insertion. 

Into the back part of the neck of the stapes. 

The tensor tympani 'muscle draws inwards the membra na tym- 
pani and thus increases the tension of that membrane ; the laxator 
tympani muscle produces an antagonistic effect upon the mem- 
brana tympani ; while the stapedius muscle, by inclining the stapes 
backwards, is supposed to compress the fluid contents of the ves- 
tibule. 



5 go ORGAN OF HEARIXG. 



The ARTERIES of the tympanum are derived from the follow- 



Forming an arterial circle around the \ Tympanic branch of internal maxillary. 

?nembrana tympani. \ Stylo-mastoid branch of posterior auricular. 

t%- a. m- i. j * *z * w- t t -u 4 ( Petrosal branch of middle meningeal. 

Distributed to other -portions of the tym- } ~, . , , r . ^ , =., 

^ ■> •< Tympanic branch of internal carotid. 

r anm • ( Branches of ascending pharyngeal. 

The VEINS empty into the middle meningeal and the 
pharyngeal veins. 

The NERVES are derived from the following sources : 

Branch of otic ganglion ■{ To tensor tympani muscle. 

Tympanic of facial nerve ■{ To stapedius and laxator tympani muscles. 

Tympanic of glosso-pharyn- f Tq ^ mucous membrane> . Czrolid lexuS- 
geal (Jacobson s nerve). I j Qreat ^^ nerye _ 

Chorda tympani branch of] Communicating branches to / Otic ganglion, 
facial nerve. L 

The cavity of the tympanum is lined with a mucous membrane, 
and, through the Eustachian tube, communicates with the cavity 
of the pharynx. It is through this latter communication, that air 
is permitted to enter the cavity of the tympanum, and thus the 
membrana tympani is allowed to vibrate between two bodies of 
air whose density is equal, and thus to truly perceive the quality 
and tone of the notes which it is called upon to record. 

The abnormal sounds, perceived when the Eustachian tube 
is obstructed by swelling of the mucous lining during attacks of 
severe influenza, are due, in great measure, to the impaired en- 
trance and exit of air. It is customary for gunners, when fir- 
ing large cannon, to stand with the mouth open, since, by so 
doing, the vibrations of the air produced by the explosion are 
transmitted through the Eustachian tube as well as through the 
auditory canal, and, by neutralizing each other, the drum mem- 
brane stands almost motionless, and little if any sound is per- 
ceived. 



THE INTERNAL EAR OR LABYRINTH. 

The internal ear consists of a series of cavities channelled out 
of the temporal bone, called the osseous labyrinth. It is lined, 
throughout its whole extent, by a thin fibro-serous membrane, 
whose function is to secrete a fluid called the liquor Cotnnnii 
or the perilymph, in which fluid floats a membranous sac, which 
resembles in its shape the outline of the osseous labyrinth, and 



THE LAB YRINTH. 



591 



which is called the membranous labyrinth. The membranous 
labyrinth, is itself filled with a fluid, called the endolymph. 

The Osseous Labyrinth. 

The osseous portion of the internal ear may be subdivided 
into three distinct parts, to which the following names have been 
applied : 

The vestibule. 
The semi-circular canals. 
The cochlea. 
The VESTIBULE is the main cavity of the labyrinth, and is 
situated in its central portion, at the inner side of the cavity of 
the middle ear. It communicates, at its anterior part, with the 
scala vestibuli through a large opening, and, by five small open- 
ings, on its posterior wall, with the semi-circular canals. 

Upon its outer wall is a large opening called the fenestra 
ovalis, through which it would communicate with the cavity of 
the tympanum, were this opening not closed by the annular 
ligament of the stapes, and by the lining membrane of both 
cavities. 

The inner wall of the vestibule presents the following points 
of interest, to which special names have been applied : 
The fovea hemispherica. 
The macula cribrosa. 
The pyramidal eminence. 
The opening of the aquaeductus vestibuli. 
The fovea hemispherica is a small circular depression, which 

corresponds to the situation of the saccule. 
The macula cribrosa are numerous small openings, which give 
passage to branches of the saccular division of the ves- 
tibular nerve. 
The pyramidal eminence consists of a vertical ridge of bone, 
which separates the fovea from the opening of the 
aquaeductus vestibuli. 
The aquaeductus vestibuli is a canal, which extends to the 
posterior part of the petrous portion of the temporal 
bone, and opens into the middle fossa of the cranium. 
The roof of the vestibule presents the following points oi in- 
terest. 

Part of the fovea hemispherica. 
Part of the pyramidal eminence. 
The fovea semi-elliptica. 
The first two, of these three points of interest, have already 



592 



ORGAN OF HEARING. 



been described as pertaining chiefly to the inner wall of the ves- 
tibule. 

The fovea semi-elliptica is a small oval depression, whose trans- 
verse diameter is the longest, and which corresponds to the situa- 
tion of the utricle. It is perforated by small foramina, forming 
the so-called mactda cribrosa, for the transmission of filaments of 
the utricular and ampullar branches of the vestibular nerve. 

The SEMI-CIRCULAR CANALS are three in number, and are 
situated posterior to, and above the cavity of the vestibule. They 
are called the superior, the posterior, and the external canals. 
Each one lies at a right angle to the other two. 

The superior canal is directed vertically, and its axis lies at a 
right angle with the posterior surface of the petrous portion of 
the temporal bone. 

The posterior canal is also directed vertically, but its axis lies 
parallel to the posterior surface of the petrous portion of the 
temporal bone. 

The external canal is directed horizontally outwards and back- 
wards. 

Each canal presents a dilated extremity, called the ampulla, 
and the superior and posterior canals join with each other at their 
outer extremities, while the inner extremities of the superior and 
the posterior canals, and both extremities of the external canal 
open into the cavity of the vestibule. 

The ampullce of the three canals are all situated at that extrem- 
ity which opens into the vestibule. The horizontal or external 
canal has, however, only one ampulla, although both ends com- 
municate with the vestibule. 

The function of the semi-circular canals is not positively de- 
termined. By some, they are supposed to appreciate the direc- 
tion of sound, while by others, they are supposed to have some 
influence in maintaining equilibrium. 

The COCHLEA is an excavation in the substance of the petrous 
portion of the temporal bone, which resembles the interior of the 
shell of the snail, and which is situated in front of the vestibule. 
The base looks inwards, and corresponds to the bottom of the 
internal auditory canal. It is pierced by numerous small fila- 
ments of the cochlear branch of the auditory nerve. 
The apex is directed forwards and outwards. 
It presents the following points of interest, to which special 
names have been applied. 

1. The modiolus or central axis. 

2. The spiral canal. 






THE COCHLEA. 



593 



3. The lamina spiralis. 

4. The scala tympani. 

5. The scala vestibuli. 

6. The scala media. 

The modiolus is the central axis of the cochlea, and is broader 
at its base than at its apex, thus presenting a conical form. The 
apertures, mentioned as pertaining to the base of the cochlea, 
are in reality, openings in the base of the modiolus. Its apex 
becomes expanded and blends with the walls of the cupola. The 
cavity of the modiolus is called the tubulus centralis modioli, 
and, from this central canal, numerous smaller canals open to the 
outer surface of the modiolus and transmit small vessels and the 
filaments of the cochlear nerve. 

The spiral canal is a space between the modiolus and the 
outer wall of the cochlea. It is so called from its spiral di- 
rection, since it makes two and a half complete turns around 
the modiolus. It gradually decreases in size as it ascends, and 
terminates in a cul-de-sac, called the cupola, which corresponds 
to the apex of the cochlea. It communicates with three open- 
ings as follows : 

The fenestra rotunda, which is closed during life by the 
membrana tympani secundaria. 

The opening i-nto the cavity of the vestibule, which has already 
been described. 

The opening of the aquceductus cochlea;, which transmits a 
small vein to the inferior surface of the petrous por- 
tion of the temporal bone. 

The lamina spiralis is a bony projection, which separates the 
spiral canal partially into its component parts, by winding around 
the modiolus and by extending only about one-half of the dis- 
tance across the cavity of the cochlea. This thin osseous zone 
consists of two layers, between which the filaments of the coch- 
lear nerve pass, and the intervening space between its edge and 
the outer wall of the cavity of the cochlea is filled by a mem- 
brane, called the membrana basilaris, which is continuous with 
the periosteum covering the lamina spiralis. 

The scala tympani is that portion of the spiral canal of the 
cochlea, which lies below the lamina spiralis and the membrana 
basilaris. Its name is applied from its termination at the fenes- 
tra rotunda, which is situated upon the inner wall oi~ the tym- 
panum, and which is closed by the membrana tympani secundaria. 
It communicates with the aquaeductus cochleae. 

The scala vestibuli is situated above the lamina spiralis 



594 



ORGAN OF HEARING. 



membrana basilaris. It is not as large a canal as the scala tym- 
pani, since the scala media is cut off from it by a membrane, called 
the membrane of Reissner. The scala vestibuli communicates 
with the cavity of the vestibule ; and, at the apex of the cochlea, 
the two scalse communicate with each other, in a space, called 
the helicotrema, created by the absence of the lamina spiralis in 
the last half coil of the canal. 

The scala media is a triangular portion of the space above the 
lamina spiralis and the membrane basilaris, which is separated 
from the scala vestibuli by a membrana, called the membrane of 
Reissner, and which contains the organ of hearing, called from its 
discoverer the organ of Corti. This space has been described by 
some authors under the names of the canalis cochlea, and the 
canalis membranacea. 

The following diagram will perhaps make the construction of 
the three divisions of the spiral canal of the cochlea more clearly 
understood by the student. 







A Longitudinal Section of the Spiral Canal of the 
Cochlea (diagrammatic.) 



S. V. Scala vestibuli. I. Membrane of Reissner. 

S. T. Scala tympani. 2. Organ of Corti, covered by the *' mem- 

S. M. Scala media. brana tectoria" or the " metnbrane of 

Corti.' 1 . 

3. Membrane basilaris. 4. Liganienhim spiralis. 

5. Upper layer of lamina spiralis ossea. 6. Lower layer of lamina spiralis ossea. 

7. Nerve filament escaping from the mo- 8. Ganglion spirale of the nerve to the organ 
diolus and supplying the organ of Corti. of Corti. 



THE LABYRINTH. 595 

The Membranous Labyrinth. 

The membranous labyrinth is a closed sac which is contained 
within the osseous labyrinth. It is prolonged into the semi-cir- 
cular canals, and lines the vestibule, and, according to some 
authorities, the canalis cochleae of Reissner. 

The portion contained within the vestibule consists of two 
sacs, called the saccule and the utricle, which do not communicate 
with each other, except indirectly through the aquseductus vesti- 
buli. 

The saccule is afforded a free communication with the prolon- 
gation of the membranous labyrinth into the scala media, through 
a small canal called the canalis reuniens, and lies in relation with 
the fovea hemispherica. 

The utricle opens into the prolongations of the membranous 
labyrinth within the semicircular canals, and lies within the de- 
pression of the fovea semielliptica. 

The membranous semicircular canals are only one-third of the 
size of the osseous canals, except at the ampulla, where they nearly 
fill the entire space. They open into the utricle by five open- 
ings, since one opening is common to two canals. 

The membranous labyrinth, as a whole, is filled with a fluid, 
called the endolymph, and is separated from the osseous labyrinth 
by an external fluid, called the perilymph. Upon its membranous 
structure, which lies between these two fluids, ramify the minute 
filaments of the vestibular nerve. 

Small bodies, called otoliths, are found upon that portion of 
the membrane, which invests the saccule and utricle, in close re- 
lation to the point of distribution of the nerves. These bodies 
are supposed by some to afford, by jarring against the nerve fila- 
ments, appreciation of the intensity of sound. 

The NERVES of the internal ear are derived from the auditory 
nerve, which, at the bottom of the internal auditory canal, divides 
into two branches called the vestibular and the cochlear nerves. 

The vestibular nerve divides into three branches, which pass 
through small openings at the bottom of the internal auditory 
canal and are distributed to the ampullae, the utricle, and the sac- 
cule. In the two latter situations, these nerve filaments bear a 
close relation to the masses of calcareous material, previously de- 
scribed as the otoliths. 

The cocJdcar nerve divides into numerous small filaments, which 
enter openings in the base of the modiolus, and, after passing 
into its central canal, escape from the small canals which are di- 
rected outwards towards the lamina spiralis, and are distributed 



596 ORGAN OF HEARING. 

to the organ of Corti, in. the scala media of the cochlea, and to 
the membrana basilaris. 

The ARTERIES of the internal ear are derived chiefly from 
three sources, viz. : 

1. The auditory artery (a branch of the basilar artery). 

2. The stylo-mas.toid artery (a branch of the posterior auri- 

cular artery). 

3. The petrosal branch of the middle meningeal artery. 

MECHANISM OF HEARING. 

In the act of hearing, the vibrations, produced within the mem- 
brana tympani by the waves of sound, are transmitted to the mem- 
brane covering of the fenestra ovalis, by means of the chain of 
bones within the cavity of the tympanum, and, through secondary 
vibrations produced within this membrane, the impulse is trans- 
mitted to the fluids of the vestibule. According to some author- 
ities, the jarring of the otoliths against the filaments of the 
vestibular nerve affords, at this latter point, a perception of the 
intensity of the sound which is being appreciated by the ear. 

The vibrations now travel along the fluids of the scala vesti- 
buli of the cochlea and of the semicircular canals, thus passing 
in two different directions. In the semicircular canals, according 
to some observers, the direction from which the sound springs is 
perceived, while the vibrations carried along the scala vestibuli 
are transmitted to the filaments of the auditory nerve in the 
organ of Corti and those connected with the membrana basilaris, 
thus affording the perception of the note and the quality of the 
sound perceived. After reaching the apex of the cochlea, the vi- 
brations are transmitted from the scala vestibuli downwards along 
the course of the scala tympani till they reach the membrana 
tympani secundaria, which covers the fenestra rotunda, where the 
vibrations are lost ; being no longer transmitted, on account of 
the absence of any conducting medium. 

The free entrance of air to the cavity of the tympanum, or the 
middle ear, affords an equal density of air upon either side of the 
membrana tympani, and thus insures a vibration of that mem- 
brane in absolute unison with the vibrations of the sound which it 
is called upon to record. 

The function of the organ of Corti, of the membrana basilaris, 
or of the otoliths, cannot be stated with any positive degree of cer- 
tainty, since new discoveries are constantly being made ; although 
some theories of their function have been given above. 

The minute construction of the scala media and its contained 
organs can be found by reference to more exhaustive treatises. 



THE PERINEUM. 597 



THE PERINEUM. 

That portion of the outlet of the pelvis, which lies anterior to 
the line drawn between the two tuberosities of the ischia, is called 
the perineum, while the portion, which lies posterior to this line, 
is called the ischio-rectal fossa. 

The structures which compose the perineum differ in the two 
sexes, but, as the male perineum is the chief seat of operation 
for stone in the bladder and for surgical conditions of the deep 
urethra, and therefore possesses great surgical importance, the 
following text will be specially understood to apply to that sex, 
unless the female perineum be specially mentioned. 

The perineal space is triangular in shape, and is bounded as 
follows : 

Anteriorly, by the symphysis pubis. 

Laterally, by the rami of the pubes and the ischia. 

Posteriorly, by the line between the tuberosities of the ischia. 

The average width of the perineum is about two and three- 
quarter inches, and the variations from this standard are of im- 
portance in the operation of lithotomy. 

The cutaneous surface of the perineum is convex, in the me- 
dian line, and slightly depressed at its outer borders. 

The perineum is composed of the following structures, each 
of which merits a special description. 

The integument. 

( Sphincter ani. 

The anal group of muscles (3) 4 Levator ani. 

( Coccygeus. 

f Accelerator urinae. 

The renito-urinary protip of muscles,.. . (4W g rector P enis - 

* s.s r Wj 1 ransversus perinei. 

[Compressor urethras. 

f Superficial perineal J Superficial layer. 
r { Deep layer. 

Fasciae ' Deep perineal (or tri- \ Anterior layer. 

angular ligament). \ Posterior layer. 

Buck's faseia. \ Obturator fascia, 
k Pelvic fascia. ; Eschio-rectal fascia. 



598 



THE PERINEUM. 



f Pudic artery. 

I Artery of the bulb. 

Arteries { Transverse perineal artery. 

[ Inferior hemorrhoidal artery. 
[ Superficial perineal artery. 

( Inferior hemorrhoidal. 

Nerves -I Superficial perineal. 

( Pudic. 

f Membranous portion of the urethra. 
I Bulbous portion of the urethra. 
| Prostatic portion of the urethra. 

Other important structures. •{ Rectum. 

I Prostate gland. 

| Cowper's glands. 

[__ Neck of the bladder. 



The SKIN of the perineum is dark in color, is freely movable, 
is covered with short crisp hairs, and is thrown into a median 
raphe, which is supplied with abundant sebaceous follicles. 

The TWO GROUPS of MUSCLES have already been described in 
the chapter pertaining to myology. 

The SUPERFICIAL FASCIA of the perineum is in close relation 
with the skin, and is composed of two layers, called the superficial 
and the deep layers. 

The superficial layer is continuous with the subcutaneous fas- 
cia of the thighs, and is heavily ladened with fat. It is thick, and 
areolar in structure. 

The deep layer is thin and aponeurotic in structure, and lies 
in close contact with the muscles of the perineum, and serves to 
bind them down to the root of the penis. It is attached, upon 
either side, to the rami of the pubes and ischia, thus enclosing 
the entire perineal structures, and. posteriorly, it becomes blended 
with the anterior layer of the triangular ligament, after passing 
beneath the lower border of the transversus perinei muscle. It 
is continuous, in front, with Buck's fascia. 

Buck's FASCIA, so called from the American surgeon, who 
first, in 1846, made its existence prominently recognized, is a con- 
tinuation of the deep layer of the superficial perineal fascia for- 
wards upon the penis as far as the glans penis ; the body of which 
organ it completely invests, and, with the suspensory ligament 
of which, it is continuous, above. This fascia, which now is fre- 
quently demonstrated, seems to establish the fact that the deep 
layer of the superficial fascia of the perineum is not continuous, 
in front, with the dartos of the scrotum, as is stated in many of 
the exhaustive treatises. In cases of urinal infiltration of the 
perineum, this fascia modifies, until perforated, the direction of 



FASCIA OF THE PERINEUM, 



599 



the infiltration, in a forward or upward direction, and is therefore 
of great surgical importance. 

The DEEP PERINEAL FASCIA, or the triangular ligament of the 
perineum, serves to support the urethra and the prostate gland, 
and to close the anterior part of the outlet of the pelvis. It is 
composed of two layers, called the anterior and the posterior 
layers, each of which take a different course, and, between which, 
is contained the space called the cavity of the triangular liga- 
ment. 

The anterior layer is thicker than the posterior, and extends 
downwards and forwards upon the membranous portion of the 
urethra, and becomes blended with the bulb of the urethra, be- 
fore it passes to its insertion into the central tendinous point of 
the perineum. It is attached, above, to the pubic arch and the 
sub-pubic ligament, and, upon either side, to the rami of the 
pubes and the ischia. 

The posterior layer of the triangular ligament has the same 
points of origin and insertion as the anterior layer, which has 
just been described. It passes upwards and backwards, and, 
after passing in front of the apex of the prostate gland, it descends 
to become inserted into the central tendinous point of the peri- 
neum, at which point it becomes continuous with the pelvic fas- 
cia. It bears an intimate relation, after leaving the apex of the 
prostate gland, to the posterior wall of the membranous portion 
of the urethral canal. 

The urethra passes through the triangular ligament, at a point 
situated about one inch below the symphysis pubis. An obstruc- 
tion to the introduction of a catheter is often encountered at 
this point, since the point of the instrument is liable to impinge 
against this fascia. 

The cavity of the triangular ligament is the space contained 
between the two layers of the deep perineal fascia. It contains 
the following structures. 

The membranous portion of the urethra. 

The compressor u ret line muscle. 

The pudic vessels. 

The pudic nerve. 

The artery of the bulb. 

The nerve of the bulb. 

The glands of Cowper, and their ducts. 

Fat, and connective tissue. 

The PELVIC FASCIA is continuous, above, with the fascia over 



600 PERINEAL VESSELS AND NERVES. 

the psoas and iliacus muscles, and with the fascia transversalis. 
It splits, at the point of attachment between it and the fibres of 
the levator ani muscle, into two layers, which are called the ob- 
turator, and the recto-vesical fascice. It covers the sacral plexus 
of nerves and the pyriformis muscle, and is perforated by the in- 
ternal iliac vessels. 

The obturator fascia forms a canal for the pudic vessels and 
nerves. It gives off a thin layer to the third portion of the 
rectum, which is called the anal or the ischio-rectal fascia, and 
is attached to the pubic arch and the sacro-sciatic ligaments. 

The recto-vesical fascia forms the pubo-prostatic ligaments, and 
encloses the prostate gland and the prostatic plexus of veins. It 
also forms the true lateral ligaments of the bladder, and sends a 
prolongation between the bladder and the rectum, which invests 
the vesiculae seminales. It is situated upon the inner surface 
of the levator ani muscle. 

The ARTERIES of the perineum have been described in the 
chapter of this work upon angiology, but the surgical importance 
of each may be here mentioned. 

The pudic artery, of each side, lies close to the ramus of the 
pubes and the ischium, and is liable to be wounded in lithotomy, 
if the incision be carried too far outwards. 

The artery of the bulb is a source of serious hemorrhage in 
lithotomy, if the incision be made too far in front ; and, in urethro- 
tomy of the deeper portions of that canal. It enters the bulb of 
the urethra, between the two layers of the triangular ligament. 

The tra?isverse perineal artery lies parallel with the muscle of 
the same name, and is almost always wounded in the lateral opera- 
tion for stone, since that muscle is usually divided. 

The inferior hemorrhoidal artery is distributed to the lower 
part of the rectum and the anus. 

The superficial perineal artery distributes its branches to the 
scrotum and the dartos. Its branches are usually divided in any 
incision which involves the superficial fascia of the perineum. 

The NERVES of the perineum are in relation with the arteries 
of the same name. 



OPERA TION OF LA TERAL LITHO TOM Y. 60 1 

PARTS ASSOCIATED WITH THE OPERATION OF 
LATERAL LITHOTOMY. 

In the operation of lateral lithotomy, certain structures are 
of necessity wounded, and certain structures should be carefully 
avoided. 

The central tendinous point of the perineum corresponds to a 
locality, situated, externally, midway between the junction of the 
scrotum with the perineum, and the centre of the anus. In the 
operation of lithotomy, the incision should never be carried above 
this point, since the membranous portion of the urethra lies im- 
mediately behind it. 

The parts, which are divided in this operation, are as follows : 
i. Integument. 

2. Superficial fascia. 

3. Inferior hemorrhoidal vessels and nerves. 

4. Superficial perineal vessels and nerves. 

5. Transversus perinei muscle. 

6. Accelerator urinae muscle (posterior fibres). 

7. Deep perineal fascia (anterior layer). 

8. Compressor urethral muscle. 

9. Levator ani muscle (anterior fibres). 

10. Membranous and prostatic portions of urethra. 

11. Prostate gland and posterior layer of the deep 

perineal fascia. 
The structures, which are to be especially avoided, are as 
follows : 

1. The bulb of the urethra and its artery. 

2. The rectum. 

3. The pudic artery. 

4. Entire division of the prostate gland. 

The first, of these four structures, is to be avoided by keeping 
the incision as far backwards as possible, without endangering 
other structures. 

The rectum is to be avoided, by not carrying the incision too 
far backwards. 

The pudic artery is to be avoided, by not carrying the incision 
too far outzvards. 

The width of the incision in the prostate gland is to be regu- 
lated by the size of the cutting instrument, and, if a scalpel be 
used, by not allowing the incision of the deeper structures to be 
carried too far backwards. 



THE FEMALE PERINEUM. 

The perineum of the female differs from that of the male in 
its size, and somewhat in its construction. 

It extends, from a line drawn between the two tuberosities of 
the ischia, upwards to the symphysis pubis, and is triangular in 
its form. It is perforated by the opening of the vulva, which cor- 
responds to the situation of the scrotum of the male, and which 
embraces the external orifice of the vagina ; and it extends upwards 
between the rectum and the posterior wall of the vagina, as a tri- 
angular-shaped prolongation, sometimes called the perineal body . 

The lower commissure of the vulva is separated from the anal 
opening by a space of about an inch, although the anus is rela- 
tively farther back than in the male. 

At the superior commissure of the vulva, may be perceived the 
clitoris, which is analogous to the penis of the male, and which 
possesses the same muscles. 

The superficial fascia, as in the male, consists of two layers, 
but both are incomplete on account of the aperture of the vulva. 
This fascia is continued forwards into the labia majora, as high 
up as the clitoris ; and it thus supports the analogy between the 
labium and the scrotum. It becomes joined to the deep perineal 
fascia, after passing beneath the lower border of the transversus 
perinei muscles. 

The triangular ligament or the deep perineal fascia of the female 
is rendered less apparent than in the male by the large aperture 
of the vagina, but it nevertheless presents two distinct layers 
which transmit the urethra, as in the male sex. 

The muscles of the female perineum comprise one not met with 
in the male, which is situated at the orifice of the vagina, and to 
which the name sphincter vagince has been applied, from its cir- 
cular arrangement. It is analogous to the accelerator urinae mus- 
cle of the male ; which is not present in the female, as the clitoris 
has no corpus spongiosum, and as the urethra is not called upon 
for forcible ejaculation. 

The arteries and nerves of the perineum of both sexes are 
identical in their situation and their general distribution. 

The perineum of the female performs an important function, 
since it tends to support the posterior wall of the vagina, and, 
indirectly, the anterior vaginal wall, the bladder, and the uterus. 
Laceration of the perineum, therefore, is, in the female, a most, 
serious condition, if not promptly relieved by surgical measures. 



INDEX 



Abdomen, apertures in, 265. 

lymphatics of, 432. 

muscles of the, 236. 

viscera of, 520. 

regions of. their boundaries and 
contents, 535, 536. 
Abdominal cavity, boundaries of, 265. 
Abdominal walls, openings in, 265 . 
Acervulus cerebri, 457. 
Acetabulum, 108. 
Acromion process, 123. 
Adenology, 2, 3, 
Air-cell, structure of, 551. 
Alimentary canal, subdivisions of, 514. 

functions of, 515 . 
Amphiarthrosis, 167. 168. 
Ampullae. 595. 
Anatomy, animal, I , 

classification of, I . 

comparative, I . 

definition of, I. 

descriptive, I . 

forensic, 2 . 

general, I. 

microscopical, 2. 

minute of bone, 11. 

morbid, 2. 

of man (diagram), 2. 

pathological, 2. 

philosophical, 2. 

relative, I . 

special, 1 . 

surgical, 1. 

topographical, 2. 

transcendental. 2. 

varieties of, I . 

vegetable, 1 . 

veterinary, 2. 
Angiology, 2, 3, 232. 
Angle of jaw, 60. 
Angles of scapula, 124. 



Ankle-joint, 195. 

Antrum of Highmore, 47, 48. 

Annulus ovalis, 507. 

Anti-helix, 585. 

Anti- tragus, 585. 

Aorta, 338. 

arch of, as a whole, its calibre, 341. 
aneurismal disease of, 342, 

343- 
movements of, 341. 
ascending portion of, 338. 
ascending portion of,branch- 

esof,339, 
ascending portion of, sinuses 

of. 339- 
ascending portion of, rela- 
tions of, 340. 
descending portion of, rela- 
tions of, 341 . 
transverse portion of, rela- 
tions of, 340. 
table of branches of, 344. 
abdominal, 401 . 

collateral circulation of, 

405- 
relations of, 402. 
branches of, 403 . 
divisions of, 33S. 
sinus magnum of, 33S . 
sinus magnum of, sur- 
gical interest of, 33S. 
thoracic, 399. 
relations of. 400. 
branches ol~, 400. 
Appendices epiploicae, 524. 
Apophysis, II . 
Arachnoid, 430. 440. 
Arnold's nerve, opening for, 39. 
Arterial system, 3.;.; - 

Arthrodia, [67, [68. 
Arthrology, 107. 



604 



INDEX. 



Aryteno-epiglottidean folds, 541. 
Aquaeductus cochleae, 39, 40. 
Aquaeductus Fallopii, 587. 
Aquaeductus vestibuli, 39, 595. 
Axillary space, 388. 

boundaries of, 389. 
contents of, 389. 
Artery, or Arteries. 

alveolar, 350, 357. 

anastomotica magna, of brachial, 

394, 395- 
anastomotica magna, of femoral, 

412, 414. 
angular, of facial, 350, 353. 
anterior communicating, 361 . 
aorta, see Aorta, 
articular, of popliteal,, 416. 
ascending pharyngeal, 350, 354. 
auditory, 382. 
auricular, of occipital, 350. 

of post, auricular, 350,354. 
posterior, 350, 354. 
anterior, 350, 355. 
axillary, 386. 

branches of, 390. 
relations of first portion 

of, 387. 
relations of second portion 

of, 3 87. 
relations of third portion 
of, 388. 
basilar, 380, 382. 
brachial, 393 . 

branches of, 394. 
relations of, 393. 
bronchial, 400 . 
buccal, 350. 

calcanean internal, 418, 419. 
carotid, common, 346. 

relations of, 347, 348 . 
carotid, external, 349. 

branches of (table) 350, 351 
relations of, 349. 
carotid, internal, 357. 

branches of (table) 359,360. 
relations of, 358, 359. 
carpal, 398, 399. 

anterior, 396, 399. 
posterior, 396, 397. 
centralis retinae, 360, 361. 
cerebellar, anterior, 380. 

inferior, 380, 382. 
superior, 380, 382. 



Artery, or Arteries. 

cerebral, anterior, 360, 361. 
middle, 360, 361. 
posterior, 380. 382. 
cervical, ascending, 380,383. 
superficial, 380, 384. 
choroid, anterior, 360, 362. 
ciliary, anterior, 360, 361 . 
long, 360, 361 . 
short, 360, 361. 
circle of Willis, arteries of, 362. 
circumflex, anterior, of axillary, 390, 

392. 
circumflex iliac, 465, 408. 

iliac, superficial, 412, 413. 
external, of deep femo- 
ral, 412. 414 . 
internal, of deep femo- 
ral, 412, 414. 
posterior, of axillary,390, 
392. 
coccygeal, 410. 
coeliac axis, 403 . 
colica dextra, 403 . 
media, 403. 
sinistra, 403. 
comes nervi phrenici, 385. 

ischiadici, 410. 
coronary, 344. 

inferior, 350. 
superior, 350. 
cremasteric, 405, 408. 
crico-thyroid, 350, 351 
cystic, 403, 404. 
dental, inferior, 350, 357. 
superior, 350, 357. 
deep temporal, 350, 355. 
digital, of plantar, 419. 
digital, of ulnar, 398, 399. 
dorsal artery of the penis, 41 1. 
dorsalis indicis, 396, 397. 
linguae, 350. 
pedis, 417. 

branches of, 417. 
pollicis, 396, 397, 417. 
scapulae, 392. 
epigastric, deep, 405, 407. 

superficial, 412, 413. 
superior, 380, 385. 
ethmoidal, anterior, 360, 361. 
posterior, 360, 361 . 
external pudic, deep, 412. 

superficial, 412, 413. 



INDEX. 



605 



Artery, or Artertes. 
facial, 350, 352. 

anastomoses of, 353. 
femoral, 412. 

branches of, 412. 
collateral circulation of, 415 . 
frontal, of ophthalmic, 360, 361. 
gastric, 403, 404. 
gastro-duodenalis, 403, 404. 
-epiploica dextra, 403. 
-epiploica sinistra, 403. 
gluteal, 405, 409, 411. 

inferior, 410. 
helicine, 564. 
hemorrhoidal, inferior, 410. 

middle, 405, 409. 
superior, 403. 
hepatic, 403, 404. 
hyoid of lingual, 350. 

superior thyroid, 350. 
ileo-colic, 403. 
iliac, common, 406. 

collateral circulation 

of, 406 . 
relations of, 406. 
external, 405, 407. 

branches of, 407. 
collateral circulation 

of, 408 . 
relations of, 407. 
internal, 405, 40S. 

branches of, 409. 
collateral circulation 

of, 411. 
relations of, 409. 
ilio-lumbar 405, 409, 411. 
infra- orbital, 350, 357. 
in general, 333. 

anastomoses of, 334, 335. 
branches of, 333 . 
direction of, 335 . 
nerves of, 337. 
position of, 333. 
structure of, 336, 337. 
innominata, 345. 

collateral circulation, 346. 
relations of, 345 . 
intercostal, anterior, 380, 385. 
aortic, 400, 401 . 
superior, 3S0, 3S5. 
internal mammary, 3S0, 3S4. 

maxillary, 350, 356. | ;r. 
interossei, deep palmar ol radial, 396, 



Artery, or Arteries. 

interossei, of ulnar, 398. 
interosseous, of dorsalis pedis, 417. 

of plantar, 419, 420. 
labial, inferior, 350. 
lachrymal, 360. [383. 

laryngeal, of inferior thyroid, 380, 
laryngeal, superior, 350, 351. 
lateralis nasi, 350. 
lateral sacral, 405, 409, 41 1, 
lingual, 350, 351. 
lumbar, 403, 405 . 
malleolar, of tibial, 417. 
masseteric, 350. 

mediastinal, of internal mamma- 
ry, 380, 385. 
posterior, 400, 401 . 
meningeal, anterior, 360. 

inferior, 350. 

middle, 350, 356. 

of ascending pharyn- 
geal, 350, 355. 

posterior, 380, 382. 

small, 350, 357. 
mesenteric, inferior, 403, 405. 

superior, 403, 404. 
metacarpal, of radial, 396, 397. 
metatarsal, 417. 
middle temporal, 350, 355. 
musculo-phrenic, 380, 385. 
nasal, of internal maxillary, 350,357. 

of ophthalmic, 360, 361. 
obturator, 405, 409, 410. 
occipital, 350, 353. 
oesophageal, 400, 401. 

of inferior thyroid, 380, 383. 
of bone, 12. 
of the bulb, 410. 411. 
of the corpora cavernosa, 410. 
of the lower extremity, 412. 
of the pelvis, 405. 
of the upper extremity, 371. 
ophthalmic, 360. 
palatine, inferior, 350. 

descending, 350, 357. 
posterior, 350. 
palmar arch, deep, 300. 

superficial, 398 
palpebral, 3(10, 361. 
pancreatico-duodenalis, inferior, 403 
superior, 403, 
pancreatica magna, 403. 
pancreaticae parvse, 403. 



6o6 



INDEX. 



Artery, or Arteries. 

perforating, of deep femoral, 412, 
414. 
of internal mammary, 

33o, 385. 
of plantar, 419, 420. 
of radial, 396, 397. 
pericardiac, 400. 

of internal mammary, 
33o, 385- 
perineal, superficial, 410, 411. 

transverse, 410, 
peroneal, 418. 

anterior, 418. 
pharyngeal, ascending, 350, 354. 

of ascending pharyn- 
geal, 350, 355. 
phrenic, inferior, 403. 

superior, 380, 385. 
plantar, 418, 419. 
popliteal, 415. 

branches of, 416. 
posterior communicating, 360, 362. 
princeps cervicis, 350, 354, 
pollicis, 396, 397. 
profunda cervicis, 380, 385, 386. 

femoris, relations of, 412, 

413, 414. 
inferior, of brachial, 394, 

395- 
superior, of brachial, 394, 

395- 
pterygoid, 350. 
pterygo-palatine, 350, 357. 
pubic. 405, 409. 
pudic, 405, 409, 410. 
pyloric, 403. 
radial, 395. 

tranches of, 396. 

relations of, 396. 
radialis indicis, 396. 
radial i-ecurrent, 396. 
ranine, 350, 352. 
receptaculi, 360. 
renal, 403, 404. 
sacra-media, 403, 405. 
scapular, posterior, 380, 384. 
sciatic, 405,409, 410. 
sigmoid, 403. 
spermatic, 403, 404. 
spheno-palatine (nasal), 350, 357. 
spinal, anterior, 380, 382. 

lateral, 380, 382. 



Artery, or Arteries. 

spinal posterior, 380, 382. 
splenic, 403, 404. 
sternal, 3S0, 385. 
sterno-mastoid, 350, 351. 
styio-mastoid, 350, 354. 
subclavian, 371. 

branches of, 379, 380. 
collateral circulation of, 

377, 378, 379- 
relations of second por- 
tions of, 376. 
relations of third por- 
tions of, 376, 377. 
subclavian, left, 

relations of first portion of, 

373, 374, 375- 
subclavian, right, 

relations of first portion of, 
372, 375- 
sub-lingual, 350. 
sub-maxillary, 350. 
sub-mental, 350. 
subscapular, 390, 391. 
superficialis volse, 396, 397. 
supra-orbital, 360. 
supra- renal, 403, 404. 
supra- scapular, 380, 383. 
tarsal, 417. 
temporal, 350. 355. 

anterior, 350, 355. 
thoracica alaris, 390, 391. 
longa, 390, 391. 
superior, 390, 391. 
thyroid axis, 380, 383. 

inferior, 380, 383. 
superior, 350, 351 
tibial, anterior, 416. 

branches of, 417. 
posterior, 418. 
branches of, 418. 
recurrent, 417. 
tonsillar, 350. 

tracheal, of inferior thyroid, 380,383. 
transversalis colli, 380, 384. 
transverse facial, 350. 355. 
tympanic, 350, 356. 

of internal carotid, 360. 
ulnar, 397T 

branches of, 398. 
recurrent, anterior, 398. 
recurrent, posterior, 398. 
uterine, 405, 409. 



INDEX. 



607 



Artery, or Arteries. 
vaginal, 405, 409. 
vasa brevia, 403. 
vasa intestini tenuis, 403. 
vertebral, 381, 3S2. 
vesical, 405, 409. 
vidian, 350, 357. 

Articulation, or Articulations. 

articulations and muscles of the 

cranium, table of, 61. 
acromio-clavicular, 178. 
atlo-axoid, 171. 
carpo-metacarpal, 184. 
chondro chondral, 174. 

-costal, 174. 

-sternal, 174. 
classsification of, 167. 
costo-transverse, 173. 

-vertebral, 173. 
diagrams of the varieties of, 168. 
femoro-tibial, 190. 
metacarpo-metacarpal, 184. 
-phalangeal, 185. 
metatarsal, plan of, 161. 
metatarso-metatarsal, 199. 
-phalangeal, 199. 
occipito-atloid, 170. 

-axoid, 171. 
of ankle-joint, 195. 
of astragalus, 158. 
of carpus, 142. 
of clavicle, 127. 
of cranium and spine, 170. 
of coccyx, 107. 
of cuboid bone, 159. 
of cuneiform bone, 160. 
of elbow-joint, 180. 
of ethmoid bone, 31. 
of femur, 151. 
of fibula, 155. 
of frontal bone, 34. 
of hip-joint, 186. 
of humerus, 132. 
of inferior maxillary bone, 60. 
of inferior turbinated bone, 57. 
of lachrymal bone, 52. 
of lower extremity, 186. 
of malar bone, 53. 
of superior maxillary bone, 51. 
of metacarpal bones, 144. 
of nasal bone, 46. 
of occipital bone, 21. 



Articulation, or Articulations. 

of os calcis, 158. 

of palate bone, 56. 

of patella, 152. 

of pelvis, 175. 

of phalanges of foot, 163. 

of radius, 140. 

of ribs, 173. 

of sacrum, 107. 

of scaphoid, 159. 

of scapula, 125. 

of shoulder-joint, 179, 

of sphenoid bone, 26. 

of sternum, 100. 

of tarsus, 196. 

of temporal bone, 41. 

of tibia, 154. 

of ulna, 136. 

of upper extremity, 177. 

of vertebrae, 172. 

of vomer, 45. 

of wrist-joint, 182. 

phalangeal, 199. 

pubic, 175. 

radio-ulnar, 181. 

sacro-coccygeal, 176. 
-iliac, 175. 
-vertebral, 176. 

sterno-clavicular, 177. 

tarso-metatarsal, 198. 

temporo-maxillary, 176. 

tibio-fibular, 194. 
Back. 

muscles of, 249. 
Bladder, 560. 

coats of, 562. 

general structure of, 562. 

ligaments of, 561, 562. 

nerves of, 563. 

position of, and its variations, 560. 

vessels of, 563. 

Bone or Bones. 

arteries of, 12. 

astragalus, 158. 

articulation of, 15S. 
atlas, 79, 86, 89. 
axis, 7o, 86, So 
classification of, 7, 8, 9. 
clavicle, 125. 

articulation o(, 127. 

development oi, 1 2-. 
muscles attached to. 1:7. 



6o8 



INDEX. 



Bone, or Bones. 

coccyx, 104, 107. 

articulation of, 107. 
development of, 107. 
muscles attached to, 107. 
composition of, 13. 
cuboid 159. 
of foot, 156. 

articulations of, 159. 
muscles attached to, 159. 
cuneiform bone of carpus, 141, 143. 
depressions in, (table of), II. 
ethmoid, 28. 

articulations of, 31. 
development of, 31. 
functions of, 28. 
femur, 149. 

articulations of, 151. 
development of, 151. 
muscles attached to, 151. 
fibula, 154. 

articulations of, 155. 
development of, 155. 
muscles attached to, 155. 
flat, 8. 
frontal, 32. 

articulations of, 34. 
development of, 35. 
muscles attached to, 35. 
gladiolus of sternum, 98, 99. 
. humerus, 127. 

articulations of, 132. 
development of, 131. 
muscles attached to, 131. 
ilium, 108, 109. 
inferior maxillary, 57. 

articulation of, 60. 
development of, 60. 
muscles attached to, 60. 
inferior turbinated, 56. 

articulation of, 57. 
development of, 57. 
inorganic constituents of, 13. 
irregular, 8. 
ischium, 108, ill. 
lachrymal, 51. 

articulations, 52. 
development of, 52. 
muscles attached to, 51. 
long, 8. 
malar, 52. 

articulations of, 53. 
development of, 53. 



Bone, or Bones. 

malar, muscles attached to, 53. 
manubrium of sternum, 98, 99. 
metacarpal, 143. 

articulations of, 144. 
muscles attached to, 144. 
metatarsal, 160. 

plan of articulations of, 161. 
middle turbinated, 28, 30. 
minute anatomy of, II. 
nasal, 46. 

articulations of, 46. 
development of, 46. 
occipital, 18. 

articulations of, 21. 
development of, 21. 
foramina of, 21. 
muscles attached to, 20. 
of Bertin, 23. 
of head, 7. 

of lower extremities, 7. 
of the carpus, 141. 
of the cranium, 17. 
of the face, 45 . 

classification of, 45. 
' of the foot, 156. 

diagram illustrating plan of, 157. 
of the hand, 140. 

table of, 140. 
of the head, 16 to 76. 
of the leg, 152. 
of the lower extremity, 149. 
of the tarsus, 156, 158. 
of the trunk, 121. 
of the upper extremity, 7. 
organic constituents of, 13. 
os calcis, 158. 

articulations of. 158. 
muscles attached to, 158. 
os innominatum, 104, 108. 

muscles attached to, 115. 
os magnum of carpus, 142, 143. 
pairs of, 9. 
palate, 53. 

articulations, 56. 
development of, 56. 
muscles attached to, 56. 
parietal, 43. 

articulations of, 44. 
development of, 44. 
muscles attached to, 44. 
patella, 152. 

articulations of, 152. 



INDEX. 



609 



Bone, or Bones. 

patella, muscles attached to, 152. 
pelvis, 79. 

phalanges of foot, 157, 162. 
articulations of, 163. 
muscles attached to, 163. 
phalanges of hand, 145. 

muscles attached to, 145. 
pisiform bone of carpus, 141, 143. 
prominences of, 9, 10. 
pubes, 108, 113. 
radius, 137. 

articulation of, 140. 
development of, 140. 
muscles attached to, 140. 
ribs, 93. 

false, 94. 
floating, 94. 

guide to location of, 103. 
peculiar, 96. 
true, 94. 
sacrum, 104. 

articulation of, 107. 
development of, 106. 
muscles attached to, 106. 
promontory of, 104. 
scaphoid bone of carpus, 141, 143. 
of foot, 156. 

articulations of, 156. 
muscles attached to, 156. 
scapula, 121. 

angles of, 124. 
articulations of, 125. 
development of, 125. 
muscles attached 10,124,125. 
spine of the, 122. 
semilunar bone of carpus, 141, 143, 
shape of, 8. 
short, 8. 

single or mesial, 9. 
special doctrine of the anatomy 

of, 3. 
sphenoid, 21. 

articulations of, 26. 
development of, 27. 
muscles attached to the, 27 
parts formed by, 21. 
processes of, 22. 
sphenoidal turbinated, 23. 
sternum, 98. 

articulations of, 100. 
development of, 101. 
muscles attached to, 100. 



Bone, or Bones. 

superior maxillary. 47. 

articulation of, 51. 
development of, 51. 
muscles attached to, 50. 
superior turbinated, 28, 30. 
tarsus, bones of the, 156, 158. 
temporal, 35. 

articulation of, 41. 
development of, 41. 
muscles attached to, 40. 
table of foramina in ex- 
ternal surface of, 42. 
tibia, 152. 

articulation of, 154. 
development of, 154. 
muscles attached to, 153. 
trapezium, bone of carpus, 141, 143. 
trapezoid, bone of carpus, 142, 143. 
ulna, 132. 

articulations of, 136. 
development of, 136. 
muscles attached to, 136. 
unciform bone of carpus, 142, 143. 
unclassified, 7. 
varieties of, 8. 
veins of, 12. 
vertebrae, 79. 
cervical, 82 

characteristics peculiar to cer- 
tain, 85. 
component parts of a, 80. 
development of, 89. 
diagrammatic plan of, 80. 
dorsal, 83. 

1st, 9th, 10th. nth, 12th, 88. 
false, 79. 

general characteristics of the,8o. 
table of important anatomical 

relations of special, 93. 
lumbar, S4. 
lumbar 5th, SS. 
prominens, 79. SS, 90. 
regional characteristics of, S2. 
relation of the transverse pro- 
cess of the, 91. 
sacrum, 104. 
structure of, S9. 
true. 79. 
vessels of, 12. 
vomer, 45. 

articulations o(, 45. 
development oi\ 40. 



6io 



INDEX. 



Brachia, anterior, 457. 

posterior, 457. 
Brain, 441. 

cavities in, 444. 

cells of, 462. 

commissures of, 443. 

construction of (diagrammatic) 441, 

448,451. 

floor of, 452. 
ganglia of, 442. 
general summary of, 461. 
grey matter of, 461. 
guides to the situation of the dif- 
ferent portions of, 462. 
internal capsule of, 448, 454. 
" ganglia of, 448, 454. 
Bronchi, cartilage plates of, 547. 
distribution of, 548. 
relations of, 547. 
rings of, 547, 
Bronchus, left, 547. 

right, 547. 
Buck's fascia, 598. 
Bulb of the corpus spongiosum, 564. 

of the vestibule, 573. 
Caecum, 521. 
Calvarium, 441. 
Canal, auditory external, 584. 
internal, 592. 
carotid, 38, 75. 
dental anterior, 48. 
inferior, 59. 
posterior, 48. 
ethmoidal anterior, 34, 65. 
posterior, 34, 65. 
femoral, 242. 
Huguier (of), 36, 40. 
infra-orbital, 48, 65. 
lachrymal, 583. 
malar, orifices of, 65. 
of Nuck, 575. 
palatine anterior, 50, 67, 74. 

posterior, 50. 
pterygo-palatine, 24, 56^ 74. 
Petit (of), 581. 
sacral, 106. 
Schlemm (of), 579. 
semicircular, 591. 
spiral of cochlea, 592, 593. 
tensor tympani muscle (for) 40, 76. 
Vidian, 26. 
Wirsung (of), 533. 
Canalis cochleae, 593. 



Canalis reuniens, 595, 
Canaliculi, 11. 
Canthus, external, 582. 
internal, 582". 
Capsule, Muller (of), 557, 558. 
Caput gallinaginis, 565 . 
Carpus, articulations of, 142, 183. 
Cartilage, arytenoid, 538. 

bronchus (of ), 547. 
costal, 97. 
cricoid, 537, 538. 
cuneifoi-m, 539. 
Santorini (of), 538. 
septum of nose, 68. 
tarsal, 583. 
thyroid, 537. 
trachea, 545. 
varieties, 167. 
Wrisberg (of), 539. 
Caruncula lachrymalis, 582. 
Cauda equina, 438. 
Caudate nucleus, 454. 
Cavities of the trunk, 264. 

sigmoid (lesser and greater), 134. 
Cells, Purkinje (of), 460. 
Cerebellum, 442. 

description (of), 459. 
fissures (of), 460. 
processes (of), 460. 
Cerebro- Spinal Axis, arrangement of, ta- 
bles of, 461. 
divisions of, 437. 
grey matter of, 461. 
membranes of, 439. 
nerves of, 438. 
fluid, 440. 
Cerebrum, 442, 448. 

cuneus of, 450. 
ganglia of, 461. 
inferior surface of, 452. 
internal surface of, 450. 
precuneus of, 450. 
principal lobes, 449. 
" fissures, 449. 
Cervix uteri, 574. 
Chopart's operation, 158. 
Chordae tendineae, 510. 
Choroid plexuses, 440, 445, 447. 
Circle of Willis, 362. 
Clitoris, 572. 

its structure, 572. 
its ligaments, 57^2. 
its prepuce, 572. 



INDEX. 



6n 



Cochlea, 591, 592. 

structure of, 592. 
nerves of, 595. 
vessels of, 596. 
Colliculus, 580. 
Colon, 52T, 522. 
Columnas Carnese, 508. 
Columns, posterior vesicular, 463. 
Columns Bertin (of), 557. 
Commissures of brain, 443. 

third ventricle (of), 446. 
Commissura simplex, 459. 
Conarium, 457. 
Concha, 584. 
Conglobate glands, 430. 
Conjunctiva, 583. 
Cones Jacobs' (of), 580. 
Coni vasculosi, 569. 
Conus arteriosus, 509. 
Cord, spermatic, 571. 
Cornea, 578. 
Cornicula laryngis, 538. 
Corona radiata, 453. 
Coronoid process of ulna. 132. 
Corpora albicantia, 453, 455. 
cavernosa, 563. 
mamillaria, 453. 
striata, 442, 445. 
Corpus Arantii, 510, 511. 

callosum, 444, 448, 450, 452, 456. 
description of, 456. 
beak of, 456. 
knee of, 456. 
peduncles of, 456. 
raphe of, 456. 
fimbriatum, 445. 
highmorianum, 568. 
luteum (false), 577. 
(true), 577. 
spongiosum, 564. 

(bulb of), 564. 
striatum, 453. 

construction, 453. 
head, 453. 
tail, 454. 
proportions, 454. 
surcingle, 454. 
Costal cartilages, 97. 
Cotyloid cavity, 108. 
notch, 108. 
Cranium, bones of the, 17. 
Crypts, Leiberkiihn (of), 524. 
Crura cerebri, 453. 



Crura cerebri, description of, 457. 
Cuneus of cerebrum, 450. 

Dartos, 467. 

Deglutition, mechanism of the act of, 234. 
Dentata, 167. 

Depression for Gasserian ganglion, 38. 
Dermatology, 2, 3. 
Descriptive anatomy, I. 
Diagram of layers forming abdominal wall 
of iliac region, 244. 
of varieties of joints, 168. 
Diaphysis, II. 
Diarthrosis, 167, 168. 
Dorsum sella;, 23. 
Ducts, biliary, 531. 

cystic, 532. 

hepatic, 532. 

ejaculatory, 469. 

nasal, 584. 
Duct, Bartholine (of), 517. 

Cowper (of), 5 66, 

Gaertner (of), 577. 

Rivinus (of), 517. 

Steno (of), 517. 

Wharton (of), 517. 

Wirsung (of ), 533. 

prostatic, 565. 

seminal, 566, 569. 
Ductus communis choledicus, 532. 
Duodenum, 521. 
Dura mater, 439. 

reflections of, 439. 
sinuses of, 423. 

Ear, external, 584. 

internal, 590. 

middle, 586. 
Elbow-joint, 180. 
Elements, fluid anatomical, 3. 
solid " 3. 

Eminentia articularis, 36. 

" collateralis, 445. 
Enarthrosis, 167, 168, 169. 
Encephalon, 441. 
Endocardium, 505. 
Endolymph, 595 . 

Ensiform appendix of sternum, 9S, 99. 
Epididymis, 56S. 
Epiglottis, 537, 539. 
Epiphysis, 11. 
Ethmoidal tells, 30. 

notch of frontal bone, 32, 33, 34 # 



6l2 



INDEX. 



Eustachian tube, 587. 

opening of. 76. 
osseous portion of, 40. 
Expiration, muscles of, 248. 
Eye, 578. 

appendages to, 582. 

coats of, 578, 579, 580. 

crystalline lens of, 578, 581. 

muscles of, 209, 210, 211. 

refractory media of, 578, 581, 582. 
Eyebrows, 582. 
Eye-lids, structure of, 582. 

Fallopian tubes, 576. 
Falx cerebelli, 439. 

" cerebri, 28, 439. 
Fascia, anal, 600. 

Buck's, 598. 
cremasteric, 571. 
cribriform, 242, 243. 
dentata, 445. 
intercolumnar, 243. 
ischio-rectal, 600. 
obturator, 600. 
pelvic, 599. 
perineal, (deep), 599. 

(superficial), 598. 
propria, 571. 
recto- vesical, 600. 
spermatic, 571. 
superficial, of abdomen, 243. 
transversalis, 242, 243. 
Fasciculi teretes, 447. 
Fasciculus cuneatus, 458. 

gracilis, 458. 
Femoral canal, 242. 

hernia, 243 . 
Fenestra ovalis, 586, 588, 591. 
rotundum, 5S6, 593. 
Fibres of heart, 506, 507, 508. 
Fibro-cartilage (varieties), 168. 
Filum terminale, 438. 
Fissure auricular of temporal bone, 40. 
Glasserian, 36. 
nasal of ethmoid bone. 29. 
pterygo-maxillary, 72. 
Fissures, cerebellum (of), 460. 

cerebrum (of), 449, 450. 
liver (of), 528, 529. 
Rolando (of), 449 450. 
Sylvius (of), 449, 450, 452. 
sphenoidal, 27, 65. 
spinal cord (of), 462. 



Fissures, spheno-maxillary, 52, 65, 72. 

transverse of brain, 445. 
Flocculus cerebellum (of), 460. 
Fluid, anatomical elements, 3. 

excrementitious, 3. 

formative, 3. 
Fluids of the body, classification (of), 3. 
Fluid, permanent, 3. 

recrementitious, 3. 
Fluids, secretive, 3. 
Fontanelle, posterior, 20. 
Foot, bones of the, 156. 

muscles of the, 319. 

plan of the bones of (diagram), 157. 

points of surgical interest, 162. 

principles of leverage exhibited in 
the, 327. 

Foramen or Foramina. 

accessory palatine, 74, 

anterior condyloid, 19, 21, 76. 
ethmoidal, 30. 
sacral, 104. 

basis cranii, 38. 

caecum, 29, 33. 

external and posterior small pal- 
atine of palate bone, 54, 55. 

for Arnold's nerve, 76. 

for fifth sacral nerve, 105. 

for Jacobson's nerve, 76. 

for malar branch of temporo- 
malar nerve, 52. 

for the small petrosal nerve, 38. 

incisor, 50. 

infra-orbital, 47. 

intervertebral, 81. 

in the surface of the temporal 
bone, table of, 42. 

jugular, 76. 

lacerum anterius, 27, 65. 

medium, 25, 38, 75. 
posterius, 76. 

magnum, 18, 21. 

mastoid, 37. 

mental, 58. 

obturator, 108. 109. 

of anterior region of skull, guide 
to, 66. 

of aqueductus cochleae, 76. 

of infundibulum, 31. 

of mastoid portion of temporal 
bone, 37. 

of Monroe, 444, 446, 455. 



INDEX. 



613 



Foramen, or Foramina, 

of occipital bone, 21. 

of orbit, 66. 

of Scarpa, 50, 74. 

of spheno-maxillary fossa, 73. 

of Stenson, 50, 74. 

of Winslow, 526. 

olfactory, 29, 67. 

optic, 27. 

ovale, 24, 27, 76. 

of heart, 507. 
of pelvis, 108, 109, 
parietal, 43. 

posterior condyloid, 19, 21, 76. 
ethmoidal, 30. 
palatine, 74. 
sacral, 105. 
rotundum, 24, 27. 
spheno-palatine, 55. 
spinal, 81. 

spinosum, 24, 27, 76. 
sternal, 99. 
stylo-mastoid, 40, 75. 
supra-orbital, 32, 65. 
temporo-malar, 52. 
Thebesii, 506. 
thyroid, 108, 109. 
vertebral, 82, 83. 
Vesalii, 24, 27, 76. 
Forearm, muscles of the, 281. 
Forensic anatomy, 2. 
Fornix, 445, 454. 

body of, 455. 
bulbs of, 453. 
crura of, 455. 
lyra of, 455. 
Fossa, canine, 47. 

cerebellar, 19. 

cerebral, 19. 

coronoid of humerus, 129. 

glenoid, 36, 76. 

iliac, 535. 

incisive, 47. 

of inferior maxillary bone, 58. 
ischio-rectal, 597. 
jugular, 39, 76. 
lachrymal, 34. 64. 
myrtiform, 47. 
nasal, 66. 

bones of, 68, 69. 
openings of, 69. 
naviculars, 566. 
of anti-helix, 5S5. 



Fossa, of helix, 585. 

'* olecranon of humerus, 129. 
ovalis, 507. 
scaphoid, 26. 
spheno-maxillary, 72. 

foramina of, 73 . 
sublingual of inferior maxillary 

bone, 58. 
submaxillary of inferior maxillary 

bone, 58. 
temporal, 71. 
zygomatic, 71. 
Fovea centralis, 580. 

hemi-spherica, 591. 
semi-elliptica, 592. 
trochlearis, 34. 
Fundus of bladder, 561. 
of uterus, 574. 

Gall-bladder, 532. 

Ganglia of brain, 442. 

General anatomy, 1. 

Generative organs, doctrine of, 3. 

Genesiology, 3. 

Genital organs of the female, 572. 

" " " male, 563. 

Germinal spot, 577. 

" vesicle, 577. 
Ginglymus, 167, 168, 169. 
Glands, arytenoid, 544. 

lachrymal, 583. 

Meibomian, 583. 

of Bartholine, 573. 

of Brunner, 524. 

of Cowper, 599. 

of Lieberkiihn, 524. 

of Littre, 567. 

parotid, 516. 

prostate, 570. 

solitary, 524. 

sublingual, 517. 

submaxillary, 517. 

thymus, 554. 

thyroid, 553. 
Glandular structures, doctrine of, 3. 
Glans penis, 563. 
Glenoid cavity, 123, 124, 12S. 
Gomphosis, 167, 168, 169. 
Graafian vesicles, 577. 
Groove, bicipital of humerus, 128. 

digastric, 37. 

for inferior petrosal sinus, 40. [96. 
" intercostal vessels and nerves. 



614 



INDEX. 



Groove for lachrymal sac, 65. 

" naso-palatine nerve, 45. 
" superior petrosal sinus, 40. 
" vomer, 50. 
infra- orbital, 65. 
musculo-spiral, 130. 
mylo-hyoid, 59. 
occipital, 37. 

subclavian of clavicle, 126. 
vertebral, 92. 
Guides to location of the different ribs, 103. 
Gyri operti, 449. 
Gyrus fornicatus, 451. 
Gyrus hippocampi, 452. 

Hamulus lachrymalis, 51. 
Hand, muscles of the, 291. 
Harmonia, 167, 168, 169. 
Haversian canals, 12. 
spaces, 12. 
system, 12. 
Head, bones of the, 17 to 60. 

lymphatics of, 431. 

muscles of the (classification of) 205 

osteology of, 16. 

vessels of, 350, 422. 
Hearing, mechanism of, 596. 
Heart, 505. 

auricles of, 506, 507. 

cavities of, 506. 

fibres of, 506, 507, 508. 

grooves of, 506. 

nerves of, 512. 

rings of, 512. 

ventricles of, 508, 509. 

vessels of, 512. 
Helicotrema, 594 . 
Helix, 585. 
Helicine arteries, 564. 
Hernia, femoral (coverings of), 243. 
inguinal (coverings of), 243, 
Hey's operation, 158. 
Hiatus Fallopii, 38. 
Hinge-joint, 169. 
Hip-joint, 186. 

movements of, 188. 
Hippocampus major, 445. 
minor, 445. 
Histology, 1. 
Hunter's canal, 412. 
Hyaloid membrane, 581. 
Hygrology, 2, 3. 
Hymen, 572. 

varieties of, 572 . 



Ileum, 521. 
Incus, 588. 

Infundibulum of brain, 453. 
of heart, 509. 
of nose, 30. 
Inguinal hernia (see hernia). 
Inspiration, muscles of, 248. 
Internal capsule of brain, 454. 

viscera, doctrine of the anatomy 
of, 3- 
Interpeduncular space, 446, 453. 
Intestinal canal, structure of, 521, 522, 523. 
Island of Reil, 449, 450. 
Isthmus of Vieussens, 507. 
Iter chordae anterius, 586. 

posterius. 586. 

Iter e tertio ad quartum ventriculum, 444, 

446, 447- 

Jacob's rods and cones, 580. 
Jacobson's nerve, opening for, 39. 
Jejunum, 521. 

Joints, doctrine of anatomy of, 3. 
Jugular surface, of petrous portion of tem- 
poral bone, 39. 

Kidney, 555. 

capsule of, 556. 

cortical substance of, 556, 557. 

medullary substance of, 556. 

nerves of, 559. 

pelvis of, 559. 

pyramids of, 556. 

tubes of, 557. 

vessels of, 558. 
Knee-joint, 190. 

Labia majora of vulva, 572. 
minora of vulva, 572. 
Labyrinth, 590. 

membranous, 595. 
osseous, 591. 
Lachrymal canal, 583. 
gland, 583. 
sac, 583. 

tubercle of nasal process of su- 
perior maxillary bone, 48. 
Lacteal vessels, 430. 
Lacunae, 12. 
Lacus lachrymalis, 582. 
Lambdoidal suture, 20. 
Lamellae circumferential, 12. 
concentric, 12. 
interstitial, 12. 



INDEX. 



615 



Lamina, cinerea, 452. 

cribrosa, 578. 

fusca, 578. 

spiralis, 593. 
Larynx, 537. 

cartilages of, 537, 538, 539. 

cavity of (its contents), 543, 

ligaments of, 542. 

mucous lining of, 544. 

muscles of, 539. 

nerves of, 544. 

vessels of, 544. 
Leg, bones of, 152. 
Lenticular nucleus, 454. 

Ligament, or Ligaments. 

acromioclavicular, 178. 
alaria, 192. 

astragalo-scaphoid, 197. 
arcuatum externum, 247. 
internum, 247. 
atlo-axoid anterior, 171. 
posterior, 171. 
transverse, 171. 
capsular, 171. 
calcaneo-astragaloid, 196. 
cuboid, 197. 
scaphoid, 197. 
central of spinal cord, 438. 
chondro-sternal, 174. 
xiphoid, 174. 
classification of, 167. 
conoid, 178. 
coraco-acromial, 179. 
humeral, 179. 
coronary, 528. 
costo-clavicular, 178. 
transverse, 174. 
vertebral, 173. 
cotyloid of hip-joint, 187. 
crico-arytenoid, 
crucial, of knee-joint, 192. 
deltoid, of ankle-joint, 195, 
denticulata, 440. 
falciform, 528. 

formed by the peritoneum, 525. 
glenoid, of metacarpophalangeal 

articulation, 185. 
glenoid, of shoulder, 179. 
hyo-epiglottic, 541. 
ilio-femoral, 187. 
ischio femoral, 188. 
ilio-lumbar, 176. 



Ligament, or Ligaments. 
interclavicular, 178. 
interosseous, of radio-ulnar articu- 
lations, 181. 
interosseous, of tibio-fibular articu- 
lations, 195. 
lumbo-sacral, 176. 
mucosum, 192. 
occipito-atloid, anterior, 170. 
posterior, 170. 
lateral, 170. 
capsular, 170. 
occipito-axoid, 171. 

odontoid (check and sus- 
pensory), 171. 
of bladder, 561. 
of elbow-joint, 180. 
of larynx, 542. 
of liver, 528, 529. 
of lower jaw, 176, 177. 
of pinna, 585. 
of the scapula, 179. 
of the vertebrae, 172. 
of uterus, 574, 575. 
orbicular, 18 1. 
patellae, 190. 
pectinatum of eye, 582. 
posticum Winslowii, 190. 
pubic, 175, 176. 
pubo- femoral, 187. 
pulmonis latum, 552. 
radio-carpal, 182. 

ulnar, 182. 
rhomboid, 17S. 
round, of hip-joint, 187. 
of liver, 52S. 
of radio-ulnar articulation, 

1S1. 
of uterus, 575. 
sacro-coccvgeal, 176. 
iliac, 175. 
sciatic, 175. 
stellate, 173. 
sternoclavicular, 177. 
stylo-maxillary, 177. 
subflava, 172. 
supra-scapular, 170. 
suspensory of clitoris, 572 . 

crystalline lens, 581. 
penis, 59S, 
tarsal, 583. 
teres oi hip-joint, 1S7. 
thyroepiglottic, 541. 



6i6 



INDEX. 



Ligament, or Ligaments. 

tibiofibular, 194, 195. 

trapezoid, 178. 

triangular, of perineum, 599* 

ulno-carpal, 182. 
Limbosa, 167. 
Limbus luteus, 580. 
Linea aspera, 150. 

ilio-pectinea, 114. 
Line intertrochanteric, 150. 

popliteal, 153. 
Liquor Cotunii, 590. 

Morgagni, 581. 
Lithotomy, surgical anatomy of, 601 . 
Liver, 527. 

circulation of, 531. 

ducts of, 532, 533. 

fissures of, 528. 

gateway of, 527. 

lobes of, 528. 

nerves of, 532. 

structure of, 532. 

vessels of, 531. 
Lobe, amygdala, 460. 
Lobes of cerebrum, 449. 

of liver, 528, 530. 

of Spigelius, 528, 530. 

slender, 460. 
Lobule of ear, 585. 

of lung, intimate structure of, 

551. 
pneumogastric, 460. 
Lobulus centralis of cerebellum, 459. 
Locus caeruleus, 447. 

niger, 457. 
Lower extremity, arteries of, 412. 

articulations of, 186. 
bones of, 149. 
lymphatics of, 432. 
muscles of the, 431. 

(classification of), 302. 
(general action of the) 327. 
veins of the, 428. 
Lungs, 548. 

apex of, 549. 

base of, 549. 

borders of, 548, 549. 

fissures of, 548 . 

intimate structure of, 550, 551. 

lobes of, 548 . 

nerves of, 552. 

relations of, 549. 

root of, 550. 



Lungs, surfaces of, 548. 

vessels of, 551, 552. 
Lunulae, 511. 
Lymphatic glands, 430. 
system, 430. 
vessels, 430, 431. 
Lymphatics of abdomen, 432. 

of head and neck, 431. 

of lower extremity, 432. 

of pelvis, 432. 

of thorax, 432. 

of upper extremity, 432. 

thoracic duct, 431. 

Macula cribrosa, 591. 
Malleolus external, 155. 
internal, 153. 
Malleus, 587. 
Malpighian bodies, 557. 

pyramids, 556. 
tuft, 558. 
Man, anatomy of, 2. 
Mastoid portion of temporal bone, 37. 
Maxillary sinus, 48. 
Meatus auditorius externus, 38. 
internus, 39. 
external auditory, 70. 
of nose, inferior, 69. 
middle, 68. 
superior, 68. 
urinarius, 564, 572. 
Mechanism of hearing, 596. 
Mediastinum, anterior, 548. 
middle, 548. 
posterior, 548. 
testis, 568. 
Medulla oblongata, 442. 

description of, 458. 
fissures of, 458. 
Membrana basilaris, 593. 
granulosa, 596. 
sacciformis, 182, 184. 
tectoria, 594. 
Membrane of Corti, 594. 

of Reissner, 594. 
Meninges of brain — arteries of, 363. 
Mesenteric glands, 430, 432. 
Mesentery, 525, 526. 
Meso-cephalon, 456. 
caecum, 525. 
colon, 525. 
rectum, 525. 
Microscopical anatomy, 2. 



INDEX. 



617 



Modiolus, 592, 593. 
Mons veneris, 572. 
Monticulus cerebelli, 459. 
Morbid anatomy, 2. 
Morphology, I. 
Mouth, 514. 

glands of, 515, 516. 
points of surgical interest in, 517, 
518. 
Muscular fibres, arrangement of, to ten- 
dons, 203. 
system, 203. 
doctrine of the anatomy of, 3. 

Muscle or Muscles. 

abductor minimi digiti, 293, 320. 

pollicis (of hand and foot), 

291, 319. 
accelerator urinae. 260. 
accessorius musculus, 255. 
acting on arm, 301, 
acting on forearm, 301. 
acting on scapula, 300. 
adductor brevis, 307. 
longus, 307. 
magnus, 307. 
pollicis (of hand and foot), 
292, 321. 
anconeus, 287. 
arytenoid, 541. 
attached to bones of cranium, 61. 

clavicle, 127. 

cuboid, 159. 

cuneiform bones, 160. 

coccyx, 107. 

femur, 151. 

fibula, 155. 

frontal bone, 35. 

humerus, 13 1. 

inferior maxilla, 60. 

lachrymal bone, 51. 

malar bone, 53. 

metacarpal bones, 144. 

occipital bone, 20. 

os calcis, 15S. 

os innominatum, 115. 

palate bone, 56. 

parietal bone, 44. 

patella. 152. 

phalanges of hand, 145. 
foot, 163. 

radius, 140. 

sacrum, 106. 



Muscle, or Muscles. 

scaphoid bone, 159. 
scapula, 124. 
sphenoid bone, 27. 
sternum, 100. 
superior maxilla, 50. 
temporal bone, 40. 
tibia, 153. 
ulna, 136. 
aryteno-epiglottideus inferior, 541. 

superior, 541. 
attachments of muscles, 203. 
attollens aurem, 206. 
attrahens aurem, 206. 
azygos uvulae, 226. 
biceps flexor cruris, 310. 
cubiti, 277. 
biventer cervicis, 224. 
brachialis anticus, 277. 
buccinator, 211. 
cervicalis ascendens, 255. 
ciliary, 582. 
coccygeus, 262. 
complexus, 223. 
compressor naris, 208. 

urethrae, 261. 
coraco-brachialis, 274. 
corrugator supercilii, 207. 
cremaster, 238. 
crico-thyroid, 539. 

arytenoid, lateralis, 540. 
posticus, 540, 
crureus, 306. 
deltoid, 272. 
depressor alae nasi, 208. 
anguli oris, 212. 
labii inferioris, 212. 
labii superioris, alreque 
nasi, 209. 
diaphragm, 246. 
digastric, 218. 
erector clitoridis, 260. 
penis, 260. 
spinae, 256. 
extensor brevis digitorum, 319. 

carpi radialis brevior, 2S6. 
longior, 285. 
ulnar is, 2S6. 
coccygis, 258, 
communis digitorum, 286. 
indicis, 288. 
longus digitorum, 315. 
minimi digiti, 2S6. 



6i8 



INDEX. 



Muscle, or Muscles. 

extensor ossis matacarpi pollicis, 
287. 
primi internodii pollicis, 

288. 
proprius pollicis, 314. 
secundi internodii pollicis, 
288. 
external pterygoid, 213. 
extrinsic of the upper extremity, 266. 
action of, 270. 
nervous supply of, 300. 
flexor accessorius, 320. 

brevis digitorum, 320. 

minimi digiti, 322. 
pollicis, 292, 321. 
carpi radialis, 282. 
ulnaris, 283. 
longus digitorum, 317. 

pollicis, 283, 316. 
minimi digiti, 293. 
profundus digitorum, 283. 
sublimis digitorum, 282. 
forms of muscles, 203. 
gastrocnemius, 315. 
gemellus inferior, 309. 
superior, 309. 
genio-hyoid, 219. 

hyo-glossus, 219 
gluteus medius. 308. 
minimus, 308. 
maximus, 308. 
gracilis, 306. 
hyo-glossus, 219. 
iliacus, 303. 

inferior constrictor, 226. 
infra-costales, 245. 
spinatus, 273. 
intercostales external, 245. 
internal, 245. 
internal ptei-ygoid, 214. 
interossei of foot, 322. 

of hand, 294. 
inter- spin ales, 258. 
inter-transversales, 258. 
intrinsic, of upper extremity, 272. 
involuntary muscles, 203, 204. 
involved in different varieties of 

talipes, 330. 
latissimus dorsi, 250, 267. 
levator anguli oris, 211. 

scapulae, 251, 268. 
ani, 261. 



Muscle, or Muscles. 

levator labii inferioris, 212. 

superioris alaeque nasi, 

208. 
superioris proprius,2io 
palati, 225. 

palpebral superioris, 209. 
levatores costarum, 246. 
lingualis, 220. 
longissimus dorsi, 256. 
longus colli, 221. 
lumbricales of foot, 320. 

of hand, 294. 
main divisions of muscles, 204. 
masseter, 213. 
middle constrictor, 226. 
multifidus spinse, 257. 
mylo-hyoid, 219. 
nomenclature of muscles, 204. 
obliquus abdominis externus, 237. 
internus, 237. 
capitis inferior, 224. 

superior, 224. 
inferior of eye, 2ro. 
superior of eye, 210. 
obturator externus, 309. 
internus, 310. 
occipito-frontalis, 206. 
of organic life, 203. 
of the back, 249. 

action of the, 259. 
of the third layer, 253. 
6f second layer, 252. 
of the superficial layer, 251. 
diagram of the fourth lay- 
er, 254. 
nervous supply of, 259 
of the crural region, 314. 
action of, 318. 
nervous supply of, 318. 
of the crural and pedal regions, 

summary of, 324. 
of the femoral region, 304. 
action of, 311. 
nervous supply of, 313. 
of the foot, 319. 

action of the interossei, 323. 
distribution of the 4th layer of 

the, 323. 
nervous supply of, 322. 
action of, 323. 
of abdomen, 236. 
action of, 238. 



INDEX. 



619 



Muscle, or Muscles. 

direction of fibres of, 239. 

nervous supply of, 239. 

points of surgical interest per- 
taining to, 239. 
of animal life, 203. 
of anterior surface of forearm, 

action of, 284. 

nervous supply of, 284. 
of arm, 277. 

action of the, 279. 

nervous supply of the, 279. 

points of surgical interest per- 
taining thereto, 279. 
of expiration, 248. 
omo-hyoid, 217, 218. 
opponens minimi digiti, 293. 

pollicis, 292. 
orbicularis palpebrarum, 207. 
of the forearm, 281. 

general summary of, 290. 

general action of, 289. 

nervous supply of, 290. 
of the hand, 291. 

action of, 295. 

nervous supply of, 295, 296. 
of the hand and forearm, 

general summary, 297. 
of the head, 205. 

action of, 214. 

classification of, 205. 

nervous supply of, 215. 
of iliac region. 302. 

action of, 303. 

nervous supply of, 303. 
of inspiration, 248. 
of the larynx, 539. 
of the lower extremity, classifica- 
tion of, 302. 
of the lower extremity, divided in 

amputations, table of, 329. 
of the lower extremity, 

general action of the, 327. 
of the neck, 215. 

classification of, 215, 216. 

action of, 227, 228, 229. 

nervous supply of, 229, 230, 231. 

surgical relations of, 233. 
of the orbit, 66. 
of the pedal region, 319. 
of the perineum, 260. 

action of, 262. 

nervous supply of, 264. 



Muscle, or Muscles. 

of the popliteal region, 313. 
of the posterior surface of forearm, 
285. 
action of, 289. 
nervous supply of, 289. 
of thorax, 245. 

action of, 247. 
nervous supply of, 249. 
of the trunk, classification of, 236. 
of the upper extremity, classifica- 
tion of, 266, 
of upper extremity, divided in am- 
putations, table of, 298. 
of upper extremity, general sum- 
mary, 299. 
palato-glossus, 225. 

pharyngeus, 226. 
palmaris brevis, 293. 
longus, 282. 
pectinati, 507. 
pectineus, 306. 
pectoralis major, 269. 
minor, 269. 
peroneus brevis, 317. 
longus, 317. 
tertius, 317. 
plantaris, 315. 
platysma myoides, 216. 
popliteus, 313. 
pronator quadratus, 284. 
radii teres, 281. 
psoas magnus, 302. 

parvus, 302. 
pyramidalis, 236. 

nasi, 208. 
pyriformis, 309. 
quadratus femoris, 310. 
rectus abdominis, 236. 

capitis anticus major, 222. 
minor, 222. 
lateralis, 222. 
posticus minor, 223. 
major, 224. 
rectus externus of eye, 209. 
femoris, 305. 
interims of eye, 210. 
superior o( eye, 209. 
retrahens aurem, 206. 
rhomboideus minor, 251, 

major, 25 2, 268. 

risorius, 213. 
rotatores spinse, 25S. 



620 



INDEX. 



Muscle, or Muscles. 

sacro-lumbalis, 256. 
sartorius, 304. 
scalenus anticus, 222. 
medius, 222. 
posticus, 223. 
scapulohumeral group, action of, 
274. 
nervous supply of, 275. 
points of surgical interest per- 
taining to, 275. 
semi-membranosus, 311. 
semi-spinalis colli, 257. 
dorsi, 257. 
semi-tendinosus, 311. 
serratus magnus, 270. 

posticus inferior, 253. 
superior, 252. 
situated upon the arm, 277. 
soleus, 315. 
sphincter ani, 262. 

vaginae, 260. 
spinalis colli et capitis, 255. 

dorsi, 256. 
splenius capitis et colli, 223. 
sterno-cleido-mastoid, 216. 
hyoid, 217. 
thyroid, 217. 
stylo-glossus, 220. 
hyoid, 220. 
pharyngeus, 221. 
sub-anconeus, 278. 
subclavius, 269. 
subscapularis, 274. 
subcrureus, 306. 
superior constrictor, 227. 
supinator longus, 285. 
brevis, 287. 
supra-spinatus, 273. 
supra- spinales, 258. 
thyro-hyoid, 217. 

-arytenoid, 540. 
-epiglottideus, 541. 
temporal, 213. 
tensor palati, 225. 
tarsi, 207. 

vaginas femoris, 304. 
teres major, 273. 
minor, 273. 
trachelo-mastoid, 223, 254. 
tibialis anticus, 314. 
posticus, 316. 
trachealis, 545. 



Musdle, or Muscles. 

transversalis abdominis, 237. 
colli, 255. 

transversus pedis, 321. 

perinaei, 261, 

trapezius, 250, 267. 

triangularis sterni, 246. 

triceps extensor cubiti, 278. 

vastus externus, 305. 
internus, 305. 

voluntary muscles, 203, 204. 

zygomaticus major, 211. 
minor, 211. 
Myology, 2, 3, 203, 204. 
Nasal duct, 66. 

fossae, 66. 

slit, 67. 

spine of frontal bone, 34. 
Nates and testes of brain, 457. 
Neck, lymphatics of, 431. 

muscles of the, classification of, 215. 

triangles of the, contents of, 365. 

Nerve or Nerves. 

abducens (6th cranial), 466. 
accessory obturator, 486, 488, 489. 
anterior-crural, 486, 487, 489, 
Arnold's, 468. 

auditory (8th cranial), 467, 469. 
auricularis, magnus, 476. 
auricular, of pneumogastric, 468. 

posterior, 467. 
auriculo-temporal, 466. 
brachial plexus of, 478, 479, 480 
481, 482. 
branches of, 478 
479,480,481. 
cardiac, 

inferior, 500. 
middle, 500. 
superior, 500. 
of pneumogastric, 468. 
cerebro-spinal, 465. 

divisions of, 465. 
cervical, 

eighth, 478. 
fifth, 478. 
first, 475. 
fourth, 476. 
plexuses of, 476, 477. 
second, 475. 
seventh, 478. 
sixth, 478. 



INDEX. 



621 



Nerve, or Nerves. 

cervical, superficial, 475. 
third, 475- 

cervico-facial, 467. 

chorda tympani, 467, 473« 

circumflex of arm, 478, 4 8l » 4 8 3- 

clavicular, supra, 475. 

cochlear, 467. 

colli, superficialis, 476. 

communicans noni, 476, 477. 

cranial, 466. 

apparent origin of, 47°- 
classified as to function, 469. 

cutaneous, 

anterior of intercostals, 

484. 
dorsal of ulnar, 480. 
external of arm, 478. 
external or musculo, 479. 
external cutaneous, 486, 

487. 

internal of anterior cru- 
ral, 487. 

internal of arm, 478, 480. 

lateral of intercostals, 
484. 

lesser internal of arm, 
478. 480. 

middle of anterior cru- 
ral, 487. 

musculo of arm, 481. 

musculo, of leg, 493, 495- 

of the toes, 496. 

palmar of ulnar, 480. 

dental, 

anterior, 466. 
inferior, 466. 
posterior, 466. 
descendens noni, 468, 474. 
descriptive anatomy of, 437, 43 8 ; 

439- 
digastric, 467. 
dorsal, of penis, 487, 491. 
facial (7th cranial), 467, 469, 473- 
frontal, 466. 

ganglia, prevertebral, 498. 
ganglion, ciliary, 471, 497. 

jugular of glosso-pharan 

geal, 473. 
jugular of pneumogas 

trie, 474- 
of Andersen, 473. 
of Gaser, 497. 



Nerves, ganglion of Meckel, 471, 497- 
of Ribes, 497. 
of root of pneumogastric, 

474- 
of trunk of pneumogas- 

474- 

submaxillary, 497. 

otic, 497. 
gastric, 468. 
genito-crural, 486, 487. 
glosso-pharyngeal (9th cranial), 467, 

469* 473- 
gluteal, 

inferior, 491. 
superior, 490, 491, 492. 
gustatory, 466, 469. 
hemorrhoidal, inferior, 491. 
hepatic, 468. 
hypoglossal (12th cranial), 468, 469, 

470. 
ilio-inguinal, 486, 487. 
ilio-hypogastric, 486, 487. 
incisor, 466. 
infra-trochlear, 466. 
intercostals, thoracic, 484. 

thoracico-abdominal, 

484. 
intercosto-humeral, 485. 
interosseous, 

anterior, 479, 
posterior, 481, 483. 
Jacobson's, 467. 

labial, of superior maxillary, 466. 
lachrymal, 466. 
laryngeal, recurrent, 46S, 544, 54°- 

superior, 468. 544. 
long ciliary, 466. 
lumbar, 486. 
lumbar plexus, 487. 

branches of, 488. 
formation of, 486. 
lumbo-sacral, 486. 
maxillary, 

inferior, 466. 
superior, 466. 
median, 478, 479, 4S2. 
motor oculi (3rd cranial), 466, 469. 

470. 
musculo-spiral, 47S, 481, 4S3- 
mylo-hyoid, 466. 
nasal, 466. 

of sup. maxillary, 466. 
neck, nerves of, 473- 47 — 



622 



INDEX, 



Nerves, noni, communicans, 475, 476, 477. 
descendens, 468, 474. 
obturator, 486, 488, 489. 
occipital, great, 475. 
small, 475. 
sub., 475. 
oesophageal, 468. 
of cervical region, 475. 
of dorsal region, summary of, 485. 
of leg and foot, summary of, 495. 
of lumbar region, summary 0^.489. 
of Lancisi, 456. 
of muscles of abdomen, table of, 

239- 
of muscles of anterior surface of 

forearm, table of. 284. 
of muscles of arm, table of, 279. 
of muscles of back, table of, 259. 
of muscles of crural region, table 

of, 318. 
of muscles of femoral region, table 

of, 3I3- 
muscles of foot, table of, 322. 
muscles of forearm, table of, 290. 
muscles of hand, table of, 295, 296. 
muscles of head, table of, 215. 
of muscles of iliac region, table of, 

303, 
muscles of neck, table of, 229, 230, 

231. 
muscles of perineum, table of, 264. 
muscles of posterior surface of fore- 
arm, table of, 289. 
muscles of scapulo-humeral group, 

table of, 275. 
of muscles of thorax, table of, 249. 
of sacral region, summary of, 492. 
of sympathetic, 497. 
of upper extremity, 478, 479, 480, 

481. 
of Wrisberg, in arm, 478, 480. 

in temporal bone, 473, 
olfactory (ist cranial), 466, 469, 470. 
ophthalmic. 466. 
optic (2nd cranial), 466, 469, 470. 
palpebral, of superior maxillary, 466. 
patheticus (4th cranial), 466. 
perineal, 491. 

superficial, 491. 
peroneal, 493. 
petrosal, 

external, 467. 
large, 467, 473. 



Nerves, peroneal, small, 467. 
phrenic, 476, 477. 
plantar, external, 494. 

internal 494, 495. 
superficial, 494. 
plexus, 

aortic, 499. 

brachial, 478, 479, 480,481. 

cardiac, 498. 

carotid, 498. 

cavernous, 498. 

cervical, 476. 

coeliac, 499. 

coronary, 498. 

epigastric, 499. 

facial, 498. 

gastric, 499. 

hepatic, 499. 

hypogastric, 499, 500. 

meningeal, 498. 

pelvic, 499, 500. 

phrenic, 499. 

renal, 499. 

solar, 499. 

spermatic, 499. 

superior mesenteric, 499. 

supra-renal, 499. 
pneumogastric (10th cranial), 468, 

469, 473- 
popliteal external, 491, 494, 495. 
internal, 491, 494, 495. 
pudendal inferior, 491. 
pudic, 490, 491, 492. 
pulmonary, of pneumogastric, 468 . 
radial, 481, 483. 

respiratory, external of bell, 478. 
internal of bell, 477. 
superior of bell, 474. 
sacral, 490. 
sacral plexus, 

branches of, 490, 491. 
formation of, 490. 
situation of, 492. 
saphenous, 

external or short, 494. 
internal or long, 487. 
scapular, supra, 478. 
sciatic, 

great, 490, 491, 492. 
small, 490, 491, 492. 
spheno-palatine, 466. 
spinal accessory (nth cranial), 468, 
469, 474. 



INDEX. 



623 



Nerves, splanchnic 

great, 501. 
lesser, 501. 
small, 501. 
subscapular, 478. 

long, 481. 
lower, 481. 
upper, 481. 
superior maxillary, 466. 
supply of toes, 496. 
supra-orbital, 466. 
supra-trochlear, 466. 
spmpathetic. 

branches of distribu- 
tion of, 497, 500. 
cords of communica- 
tion of, 497, 500. 
ganglia of, 497, 498. 
plexuses of, 498, 499. 
temporo-facial, 467. 
-malar, 466, 
thoracic, external anterior, 478,479. 
internal anterior, 478, 480. 
posterior, 478, 482. 
tibial, anterior, 493, 495. 
posterior, 494, 495. 
trigeminus (5th cranial), 466, 469. 
trochlearis (4th cranial), 466, 469, 

470. 
tympanic of facial, 467. 
ulnar, 478, 480, 483. 
upper extremity, nerves of the 478, 

479,480, 481, 482, 483. 
vaso-motor or, sympathetic of 

blood-vessels, 497. 
vestibular, 467. 
Nervous system, doctrine of the anatomy 

of, 3- 
Neurology, 2, 3, 437. 

Nose, external aperture of (surgical im- 
portance), 69. 
posterior aperture of, 74. 
cartilage of septum of, 68. 
inferior meatus of, 69. 
middle " " 63. 
superior " " 68. 
Notch, great sacro- sciatic, in, 112. 
intercondyloid, 150. 
lesser sacro-sciatic, 112. 
Nymphre, 572. 
(Esophagus, 519. 

coats of, 519. 
muscles of, 519. 



(Esophagus, nerves of, 520. 
opening of, 519. 
relations of, 519 
vessels of, 519. 
Olfactory bulbs, 442. 
Organ of Corti, 594, 596. 

Rosenmuller, 577. 
Ora serrata, 580. 
Ovaries, 576. 
Ovary, coverings of, 576. 
nerves of, 577, 
stroma of, 576, 577. 
vessels of, 576. 
Olecranon process of ulna, 133. 
Omenta of peritoneum, 525, 526. 
Omentum gastro-colic, 526. 

gastro-hepatic, 526. 
gastro-splenic, 526. 
Opening aortic, 509. 

auriculo-ventricular, 508, 509. 
in the abdominal walls, 265, 266. 
mitral, 509. 
pulmonary, 509. 
pyloric, 520. 
tricuspid, 510. 
Operculum, 449, 450. 
Osteology, 2, 3, 7. 

terms used in, 17. 
Olivary body, 458. 
Optic commissure or chiasm, 452. 
thalami, 442, 443. 
thalamus, 445. 
Orbit, bony, 64. 

table of communications with, 64. 

parts of, 64. 
foramina of, 66. 
muscles of the, 66. 
Otoliths, 595, 596. 
Ovum, 577. 
Os orbiculare, 588. 
Os planum, 29. 

articulation of, 31. 
Ovi-capsule, 577. 
Ovi-sacs, 576. 
Pancreas, 533. 

arteries of, 534. 
duct of, 533. 
nerves of, 534. 
relations of, 533. 
structure of, 533. 
Papillae, circumvallate, 516. 
filiform. 516. 
fungiform, 516. 



624 



INDEX. 



Papillae, of tongue, 516. 
Paracentral lobule of cerebrum, 45 1. 
Parietal eminence, 43. 
Parotid gland, 516. 
Pathological anatomy, 2. 
Pelvis, arteries of, 405. 

articulations of, 175. 
bony, 103, 104. 
differences in sex, 118. 
false, 117. 
in general, 117. 
lymphatics of, 432. 
points of surgical value, 1 18. 
true, 117. 
veins of the, 427. 
Penis, 563. 

cervix of, 564. 
corona of, 564. 
erectile tissue of, 563, 564. 
fraenum of, 564, 
glans of, 563, 564. 
integument of, 564. 
prepuce of, 564. 
vessels of, 564, 565. 
Pericardium, 505, 512. 
Perilymph, 595. 

Perineal space, boundaries of, 597. 
Perineum, 597. 

contents of (table), 597, 598. 
fasciae of, 597, 598, 599. 
muscles of, 260, 
nerves of, 598. 
of female, 602. 

functions of, 602. 
nerves of, 602. 
peculiarities of, 602. 
vessels of, 602. 
vessels of, 600. 
Peritoneum, 242, 243, 525. 

its distribution to viscera, 
526. 
Pes accessorius, 445. 
Pes hippocampi, 445. 
Petrous portion of temporal bone, 37. 
Peyer's patches, 524. 
Pharynx, 518. 

arteries of, 518. 
glands of, 518. 
muscles of, 518. 
nerves of, 518. 
openings of, 518. 
relations of, 518. 
vascular supply of. 364. 



Philosophical anatomy, 2. 
Phytotomy, 1, 
Pia-mater, 440. 
Pineal gland, 457. 

its two peduncles, 457. 
Pinna, 584. 
Pituitary body, 453. 
Pleura, 552. 

nerves of, 553. 
vessels of, 553. 
Plexus, cardiac, 512. 

cavernous, 498. 
coronary, 512. 
of sympathetic, 498, 499. 
pampiniform, 571. ft 

Plica semilunaris, 582. 
Pons varolii, 453. 

description of, 457, 
Popliteal space, 415. 
Portal circulation, 531. 
Precuneus of cerebrum, 450. 
Process or Processes. 
acromion, 123. 
alveolar of superior maxillary bone, 

49. 
anterior clinoid, 22. 

inferior spinous of ilium, 

in. 
superior spinous of ilium, 
in. 
auditory, 38. 
basilar, 19, 74. 

pharyngeal spine of, 19. 
brevis of malleus, 588. 
ciliary, 579. 
cochleaformis, 587. 
condyloid of inferior maxillary 

bone, 59. 
coracoid, 124. 
coronoid,of inferior maxillary bone, 

59- 
coronoid, of ulna, 132. 
crista galli, 29. 
ethmoidal, of inferior turbinated 

bone, 57. 
ethmoidal spine, 22. 
external angular, of frontal bone, 

32, 33- 
frontal, of malar bone, 52. 
gracilis, of the malleus, 36, 588. 
hamular, 26. 
internal angular, of frontal bone, 

32, 33- /Ml 



INDEX. 



625 



Process or Processes. 

jugular, of occipital bone, 19, 76. 
lachrymal of inferior turbinated 

bone, 57. 
malar, superior maxillary bone, 49. 
mastoid, 75. 

maxillary of inferior turbinated 
bone, 57. 
of palate bone, 55. 
mental, of inferior maxillary bone, 

58. 
middle clinoid, 22. 
nasal, of superior maxillary bone, 

49. 
odontoid, 87. 
of cerebellum, 460. 
of Ingrassias, 25. 
of sphenoid bone, 22. 
olecranon of ulna, 132. 
olivary, 23. 
orbital, of malar bone, 52. 

palate bone, 53, 55. 
palate, of superior maxillary bone, 

50,67. 
posterior clinoid, 22. 
posterior inferior spinous, of ilium, 

in. 
posterior superior spinous of ilium, 

III. 
pterygoid, 26, 75. 

of palate bone, 53, 55. 
rostrum of sphenoid, 23. 
sphenoidal, of palate bone, 53, 55, 

56, 
spinous, of scapula, 122. 
sphenoid, 24. 
tibia, 153. 
styloid, of fibula, 154. 
radius, 138. 
temporal bone, 39, 75. 
ulna, 134. 
unciform, 30. 
vaginal, of sphenoid, 24. 

temporal bone, 39, 75. 
vermiform, 459. 
zonulse, 581. 
zygomatic, 36. 

of malar bone, 52, 75. 
Proligerus disc, 577. 
Prostate gland, 570. 

arteries of, 570. 
nerves of, 5 70. 
structure of, 570. 



Prostate gland, vessels of, 570. 
Pyramid, anterior of tympanum, 587. 

of cerebellum, 460. 

of Ferrein, 557. 

of Malpighi, 556. 

of medulla oblongata, 458. 

of thyroid gland (third lobe), 554. 

of tympanum, 586, 587. 
Ranvier, nodes of, 438. 
Receptaculum chyli, 431. 
Rectum, 523. 
Relative anatomy, I. 
Restiform body, 458. 
Rete testes, 569. 
Ribs, articulations of the, 173. 
Right lymphatic duct, 431, 
Rima glottidis, 543. 
Rings of heart, 512. 
Rods of Jacobs, 580. 
Sacculus laryngis, 543. 
Sacro-sciatic notch, great, ill. 
lesser, 112. 
Sarcology, 2, 3. 
Scala media, 594. 

membranacea 594. 
tympani, 593. 
vestibuli, 593, 594. 
Scapula, ligaments of, 179, 
Scarpa's space, 412, 413. 
Schindylesis, 167, 168, 169. 
Sclerotic coat, 578. 
Sella turcica, 23. 

Semilunar fibro-cartilage of knee, 191. 
Septum crurale, 242, 243. 
pectiniform, 564. 
scroti, 568. 
Serrata, 167. 
Sheath crural, 243, 
Shoulder-joint, 179. 

Sigmoid notch of ramus of inferior maxil- 
lary bone, 59. 

Sinuses. 

y cavernous, 423, 424. 

circular, 423. 

coronary, 506. 

frontal, 69. 

in general, 421. 

iridis circularis, 57c). 

lateral, 423, 424. 

longitudinal, inferior, 423. 
superior, 423. 

maxillary, 48. 



626 



INDEX. 



Sinuses. 

occipital, 423. 
of dura mater, 423. 
of Valsalva, 511. 
petrosal inferior, 423, 424. 
superior, 423, 424. 
pocularis, 565. 
prostatic, 565. 
sphenoidal, 67, 69. 
straight, 423. 
transverse, 423. 
Skeletology, 2, 3. 
Skeleton, the, 7. 

of the trunk, 79. 
Skin, doctrine of, 3. 
Skull, anterior region of, 63. 

differences in the form of, 62. 
lateral region of, 70. 
under surface of base of, 73. 
Solid anatomical elements, 2, 3. 
Spaces, anterior perforated, 452. 

posterior, 453. 
Spermatic cord, structure of, 571. 
Sphenoidal crest, 23. 
Spheno- maxillary fissure of malar bone, 52. 

fossa, 72, 73. 
Spinal cord, 462. 

canal of, 463. 
central ligament of, 438. 
columns of, 462. 
commissures of, 463. 
course of fibres of, 464. 
fissures of, 462. 
grey matter of, 463. 
nerves of, 462, 463. 
nerves, construction of, 463. 

course of fibres within spinal 
cord, 464. 
Spine, anterior nasal of superior maxillary 
bone, 50. 
posterior nasal of palate bone, 54. 
of ischium, 112. 
of pubes, 114. 
of ramus of inferior maxillary bone, 

59- 
of the scapula, 122. 
pharyngeal, 75. 
Splanchnology, 2, 3. 
Spleen, 534. 

Hilum of, 534. 
structure of, 534. 
vessels of, 535. 
Squamous portion of temporal bone, 35. 



Stapes, 58S. 

Stars of Verheyen, 558, 559. 

Stereology, 3. 

Stomach, 520. 

coats of, 520. 
glands of, 521. 
nerves of, 521. 
openings of, 520. 
vessels of, 521. 

Sti-iae longitudinales, 456. 

Subarachnoidean space, 440. 

Sublingual gland, 517. 

Submaxillary gland, 517. 

Substantia gelatinosa, 463. 

Suprascapular notch, 123. 

Surgical anatomy, 1. 

Suture, 167, 168. 

its varieties, 169. 
lambdoidal, 20. 

Sutures of face, 63. 

of the skull, classifications of, 61, 
62. 

Symphysis, 167. 

Synarthrosis, 167, 168. 

Synchondrosis, 167, 168. 

Syndesmology, 2, 3, 167. 

Syndesmosis, 168. 

Synovial membranes, 168. 

Syssarcosis, 168. 

Table of articulations and muscles of bones 
of the cranium, 61. 
contrast of the cervical, dorsal 

and lumbar vertebrae, 85. 
diagrammatic of formation of the 
orbits and nasal fossae, and the 
articulations of superior max- 
illary and ethmoid bones, 70. 
of important anatomical relations 

of special vertebrae, 93. 
of muscles of lower extremity di- 
vided in amputations at joints, 

329- 
of muscles of upper extremity di- 
vided in amputations at joints, 
298. 
Taenia semicircularis, 445. 

violacea, 447, 
Talipes, muscles involved in different va- 
rieties of, 330. 
Tarsus, articulations of, 196, 
Tegmentum, 457. 
Temporal fossa, 71. 
Tendon conjoined, 237, 243. 



INDEX. 



62' 



Tendo achilles, 315, 316. 

oculi, 583, 584. 
Tentorium cerebelli, 439. 
Testicle, 567. 

coverings of, 567. 
Thalamus opticus, 454. 
Thoracic cavity, boundaries of, 265. 

duct, 431. 
Thorax, lymphatics of, 432. 
muscles of, 245. 
skeleton of, 93. 

in general, ioi. 
Tongue, 515, 516. 
Tonsil of cerebellum, 460. 
Tonsils, 515. 

Topographical anatomy, 2. 
Torcula Herophili, 19, 423. 
Trabecule of penis, 563. 
of spleen, 534. 
Trachea, 545. 

cartilages of, 545. 
structure of, 545. 
surgical relations of, 546. 
Tragus, 584. 

Transcendental anatomy, 2. 
Triangle, inferior carotid, 365. 
occipital, 369. 
subclavian, 369. 
submaxillary, 367. 
suboccipital, 381. 
superior carotid, 366. 
vertebral, 381. 
Triangles of the neck, contents of, 365. 

muscular bounda- 
ries, 231,232, 233. 
Triangular ligament of perineum, cavity 

of, 599- 
Trigonum vesicee, 562. , 

Trochanter, greater, 149. 

lesser, 150. 
Trunk, cavities of, 264. 

muscles of the, classification of,236. 
skeleton of, 79. 
Tuber annulare, 442, 443. 

cinereum, 453. 
Tubercula quadrigemina, 442, 443. 

description of, 

457. 
Tubercles genial— superior and inferior 
pairs of, of inferior maxillary bone, 58. 
Tubercle lachrymal, 49. 
of Lower, 507. 
of radius, surgical value of, 137. 



Tubercle of ramus of inferior maxillary 
bone, 59. 
of the scaphoid bone, 159. 
of tibia, 153. 
Tuberosity maxillary, 47. 
Tuberosities of humerus, 128. 
Tuberosity of ischium, in, 112. 
of ribs, 95. 
of tibia, 152. 
Tubes Fallopian, 576, 
of Bellini, 557. 
of Ferrein, 557. 
of Henle, 557. 
uriniferous, varieties of, 557. 
Tubuli seminiferi, 568. 
Tubulus centralis modioli, 593. 
Tunica albuginea, 568. 
Ruyschiana, 579. 
vaginalis, 568. 
vasculosa, 568. 
Tympanum, 586. 

bones of, 587. 
floor of, 587. 
function of, 590, 596. 
muscles of, 589. 
nerves of, 590. 
roof of, 587. 
sides of, 586, 587. 
vascular supply of, 364. 
vessels of, 590. 
Upper extremity, arteries of, 371. 

articulations of the, 177. 
bones of, 121. 
lymphatics of, 432. 
muscles of the, classifi- 
cation of, 266. 
veins of, 427, 428. 
Urachus, 561. 
Ureter, 559. 

calices of, 559. 
infundibula of, 559. 
relations of, 559. 
Urethra, bulb of, 566. 

coats of, 566, 567. 
meatus of, 564. 
membranous portion of, 566. 
of female, 573. 

peculiarities in childhood, 567. 
prostatic portion of, 565. 
spongy portion of, 566. 
subdivisions of, 565. 
Urethral canal, 565. 
crest, 565. 



628 



INDEX. 



Uterus, 574. 

appendages of, 576. 
coats of, 575. 
its muscular fibres, 575. 
ligaments of, 574, 575. 
masculinus, 565. 
mucous membrane of, 575. 
nerves of, 576. 
vessels of, 576. 
Uvea, 579. 
Uvula of cerebellum, 460. 

vesicae, 563. 
Vagina, 573. 

coats of, 573. 
glands of, 573. 
relations of, 573. 
vestibule of, 573. 
Vallecula of cerebellum, 459. 
Valves, coronary, 507. 

Eustachian, 507. 
mitral, 509. 
of Vieussens, 457. 
semilunar, 509, 510. t 
tricuspid, 510. 
Valvulae conniventes, 523. 
Vas aberrans of Haller, 569. 
Vas deferens, 569. 
Vasa efferentia, 569. 

recta, 569. 
Vegetable anatomy, 1. 



Veins. 



axillary, 427, 428. 
azygos, 425, 426. 
basilic, 427, 428. 
cardiac, 512. 
cava-inferior, 425. 
-superior, 425. 
cephalic, 427, 428. 
circulation in, 421. 
construction of, 421. 
cordis minima;, 512. 
division of, 420. 
femoral, 428. 
gastric, 426. 
hemorrhoidal, 427. 
hepatic, 531. 
iliac, common, 429. 

external, 428, 429. 

internal, 427. 
innominate, left, 425. 

right, 425. 
inter-lobular, 531. 



Veins. 

intra-lobular, 531. 
jugular, external, 424. 
internal, 425. 
lobular, 531. 
median-basilic, 427. 

-cephalic, 427. 
mesenteric inferior, 426. 
superior, 426. 
of bone, 12. 

of head and neck, table of, 422. 
of the lower extremity, 428. 
of the pelvis, 427. 
of the upper extremity, 427, 428. 
popliteal, 428. 
portal. 531. 

system of, 426, 
saphenous, long, 428. 
short, 428. 
splenic, 426. 
structure of, 420. 
subclavian, 427, 428. 
sublobular, 530. 
Thebesii, 512. 
vaginal of liver, 531. 
vorticosse, 579. 
velum interpositum, 440. 
ventricle, fifth, 447. 

fourth, 447. 
boundaries of, 447. 
lateral, 444. 

boundaries of, 445 . 
cornua of, 445. 
of brain, 444. 
of larynx, 543. 
third, 446. 

boundaries of, 447. 
Vermiform appendix, 522. 

process of cerebellum, 459. 
Vertebras, articulations of the, 172. 

table of contrast of the cervical 
dorsal and lumbar, 85. 
Vertebral column, 79. 

as a whole, 90. 
curves of, 90. 
function of, 79. 
Verumontanum, 565. 
Vesiculse seminales, 569. 
Vestibule, bulb of, 573. 

of labyrinth, 591. 
of Sibson, 509. 
Vestibule of vulva, 572. 
Veterinary anatomy, 2. 



INDEX. 



629 



Villi, 524. 

Vitreous humor of eye, 581. 

Vittelline membrane, 577. 

Vitellus, 577. 

Vocal cords, 543. 

Vessels, doctrine of, 3. 

Vessels of bone, 12. 



Wrist-joint, 182. 

Xiphoid appendix of sternum, 

Zona pellucida, 577. 

Zonula of Zinn, 581. 

Zootomy, 1. 

Zygoma, 36. 

Zygomatic fossa, 71. 



99- 



THE END. 






2JULX 



7 






*T% 



